Chemistry transport models (CTMs) play an important role in understanding fluxes and atmospheric distribution of carbon dioxide (CO_{2}). They have been widely used for modeling CO_{2} transport through forward simulations and inferring fluxes through inversion systems. With the increasing availability of high-resolution observations, it has been become possible to estimate CO_{2} fluxes at higher spatial resolution. In this work, we implemented CO_{2} transport in the Model for Prediction Across Scales – Atmosphere (MPAS-A). The objective is to use the variable-resolution capability of MPAS-A to enable a high-resolution CO_{2} simulation in a limited region with a global model. Treating CO_{2} as an inert tracer, we implemented in MPAS-A (v6.3) the CO_{2} transport processes, including advection, vertical mixing by boundary layer scheme, and convective transport. We first evaluated the newly implemented model's tracer mass conservation and then its CO_{2} simulation accuracy. A 1-year (2014) MPAS-A simulation is evaluated at the global scale using CO_{2} measurements from 50 near-surface stations and 18 Total Carbon Column Observing Network (TCCON) stations. The simulation is also compared with two global models: National Oceanic and Atmospheric Administration (NOAA) CarbonTracker v2019 (CT2019) and European Centre for Medium-Range Weather Forecasts (ECMWF) Integrated Forecasting System (IFS). A second set of simulation (2016–2018) is used to evaluate MPAS-A at regional scale using Atmospheric Carbon and Transport – America (ACT-America) aircraft CO_{2} measurements over the eastern United States. This simulation is also compared with CT2019 and a 27 km WRF-Chem simulation. The global-scale evaluations show that MPAS-A is capable of representing the spatial and temporal CO_{2} variation with a comparable level of accuracy as IFS of similar horizontal resolution. The regional-scale evaluations show that MPAS-A is capable of representing the observed atmospheric CO_{2} spatial structures related to the midlatitude synoptic weather system, including the warm versus cold sector distinction, boundary layer to free troposphere difference, and frontal boundary CO_{2} enhancement. MPAS-A's performance in representing these CO_{2} spatial structures is comparable to the global model CT2019 and regional model WRF-Chem.

Winter circulation exerts a strong control on the release and timing of nutrients and contaminants from bays into the adjoining lakes. To estimate winter residence times of solutes in the presence of ice cover, we used an ice model coupled to hydrodynamic, thermal and solute transport models of Saginaw Bay and Lake Huron for two low (2010 and 2013) and two high (2009 and 2014) ice years. The models were tested using temperature data from thermistor chains and current data from ADCP moorings deployed during the winter- time. Simulated water temperatures compared favorably to lake-wide average surface temperatures derived from NOAA’s AVHRR satellite imagery. Simulated results of ice cover are in agreement with observed data from the Great Lakes Ice Atlas. Our results indicate that ice cover significantly dampens water movement producing almost stagnant conditions around February. Estimates of residence times for Saginaw Bay (defined as the e-folding flushing time based on vertically integrated dye concentrations) show that the mean resi- dence times in a low ice year (2013) are 2.2 months for the inner bay, and 3.5 months for the entire bay. The corresponding numbers for a high ice year (2014) are 4.9 and 5.3 months, respectively. Considering the entire bay, solutes stored in the bay can be expected to be released into the lake between March (low ice year) and April (high ice year). These results are expected to aid in understanding the behavior of contami- nants in the Great Lakes during the winter months and in early spring.

1 aNguyen, Tuan, D.1 aHawley, Nathan1 aPhanikumar, Mantha, S. uhttp://www.egr.msu.edu/~phani/lno10431.pdf02090nas a2200169 4500008004100000245011800041210006900159260001200228490000800240520151400248100001801762700001601780700001301796700001801809700002101827856007201848 2017 eng d00aManifold methods for assimilating geophysical and meteorological data in Earth system models and their components0 aManifold methods for assimilating geophysical and meteorological c11/20160 v5443 aA novel manifold method of reconstructing dynamically evolving spatial fields is presented for assimilating data from sensor networks in integrated land surface – subsurface, oceanic/lake models. The method was developed based on the assumption that data can be mapped onto an underlying differential manifold. In this study, the proposed method was used to reconstruct meteorological forcing over Lake Michigan, the bathymetry of an inland lake (Gull Lake), and precipitation over the Grand River watershed in Michigan. In the first case study, hourly meteorological forcing data were reconstructed and used to run a three-dimensional hydrodynamic model of Lake Michigan and to quantify the improvement that results from the use of the new method. In the second example, the bathymetry of Gull Lake was reconstructed from measured scatter point data using the manifold technique. A hydrodynamic model of Gull Lake was developed and refined using the improved bathymetry. In the last case study, improved daily participation data for a six-year period over the Grand River watershed were used as input to an integrated, distributed hydrologic model. All three examples illustrate the superior performance of the manifold method over standard methods in terms of accuracy and computational efficiency. Our results also indicate that using the cross-validation technique to evaluate the performance of data reconstruction methods can lead to misleading conclusions about their relative performance.

1 aSafaie, Ammar1 aDang, Chinh1 aQiu, Han1 aRadha, Hayder1 aPhanikumar, M.S. uhttp://hydrology1.weebly.com/uploads/6/6/2/1/66216077/jh_safaie.pdf01517nas a2200577 4500008004100000245010300041210006900144260001200213490000800225100001500233700001500248700001900263700001900282700001400301700001800315700001500333700001700348700001500365700002200380700001300402700001500415700001500430700001300445700001500458700001400473700001700487700001900504700001400523700001400537700001500551700001300566700001600579700001600595700001900611700001600630700001600646700001600662700001500678700001400693700001400707700001400721700001400735700001500749700001600764700001900780700001800799700001600817700001500833700001900848856007200867 2014 eng d00aDetermining the rp-Process Flow through 56Ni: Resonances in 57Cu(p,g)58Zn Indentified with GRETINA0 aDetermining the rpProcess Flow through 56Ni Resonances in 57Cupg c07/20140 v1131 aLanger, C.1 aMontes, F.1 aAprahamian, A.1 aBardayan, D.W.1 aBazin, D.1 aBrown, B., A.1 aBrowne, J.1 aCrawford, H.1 aCyburt, R.1 aDomingo-Pardo, C.1 aGade, A.1 aGeorge, S.1 aHosmer, P.1 aKeek, L.1 aKontos, A.1 aLee, I.Y.1 aLemasson, A.1 aLunderberg, E.1 aMaeda, Y.1 aMatos, M.1 aMeisel, Z.1 aNoji, S.1 aNunes, F.M.1 aNystrom, A.1 aPerdikakis, G.1 aPereira, J.1 aQuinn, S.J.1 aRecchia, F.1 aSchatz, H.1 aScott, M.1 aSiegl, K.1 aSimon, A.1 aSmith, M.1 aSpyrou, A.1 aStevens, J.1 aStroberg, S.R.1 aWeisshaar, D.1 aWheeler, J.1 aWimmer, K.1 aZegers, R.G.T. uhttp://journals.aps.org/prl/abstract/10.1103/PhysRevLett.113.03250201103nas a2200361 4500008004100000245007800041210006900119260001200188490000800200100002500208700002200233700001900255700002000274700002100294700002100315700002500336700002400361700002300385700002000408700002300428700001800451700002400469700002400493700001700517700002200534700002400556700002300580700002000603700002400623700002200647700002200669856005000691 2014 eng d00aGill bacteria enable a novel digestive strategy in a wood-feeding mollusk0 aGill bacteria enable a novel digestive strategy in a woodfeeding c11/20140 v1111 aO'Connor, Roberta, M1 aFung, Jennifer, M1 aSharp, Koty, H1 aBenner, Jack, S1 aMcClung, Colleen1 aCushing, Shelley1 aLamkin, Elizabeth, R1 aFomenkov, Alexey, I1 aHenrissat, Bernard1 aLonder, Yuri, Y1 aScholz, Matthew, B1 aPosfai, Janos1 aMalfatti, Stephanie1 aTringe, Susannah, G1 aWoyke, Tanja1 aMalmstrom, Rex, R1 aColeman-Derr, Devin1 aAltamia, Marvin, A1 aDedrick, Sandra1 aKaluziak, Stefan, T1 aHaywood, Margo, G1 aDistel, Daniel, L uhttp://www.pnas.org/content/111/47/E5096.full00748nas a2200241 4500008004100000245008800041210006900129260001200198490000700210100001800217700001800235700002000253700002500273700002200298700001800320700002100338700001700359700001600376700001600392700001700408700001300425856006800438 2014 eng d00aHigh-precision B(E2) Measurements of Semi-Magic 58,60,62,64Ni by Coulomb Excitation0 aHighprecision BE2 Measurements of SemiMagic 58606264Ni by Coulom c09/20140 v901 aAllmond, J.M.1 aBrown, B., A.1 aStuchbery, A.E.1 aGalindo-Uribarri, A.1 aPadilla-Rodal, E.1 aRadford, D.C.1 aBatchelder, J.C.1 aHoward, M.E.1 aLiang, J.F.1 aManning, B.1 aVarner, R.L.1 aYu, C.H. uhttp://journals.aps.org/prc/abstract/10.1103/PhysRevC.90.03430900830nas a2200265 4500008004100000245009900041210007100140260001200211490000700223100001400230700002600244700001800270700001700288700002100305700001700326700001700343700001500360700001900375700001800394700001700412700002200429700001500451700001800466856008000484 2014 eng d00aHigh-resolution two-proton stripping to 2p-1h 7/2− states via the 59Co(3He,nγ)61Cu reaction0 aHighresolution twoproton stripping to 2p1h 72− states via the 59 c10/20140 v501 aPapka, P.1 aSharpey-Schafer, J.F.1 aBrown, B., A.1 aDinoko, T.S.1 aKhaleel, E.A.M.A1 aLawrie, E.A.1 aLawrie, J.J.1 aLi, K.C.W.1 aMajola, S.N.T.1 aRichter, W.A.1 aShirinda, O.1 aStankiewicz, M.A.1 aVymers, P.1 aWiedeking, M. uhttps://people.nscl.msu.edu/~brown/brown-all-papers/541-2014-epja50.158.pdf01353nas a2200529 4500008004100000245006100041210005900102260001200161490000700173100001900180700001500199700002300214700001600237700001800253700001900271700001400290700001200304700001900316700001900335700001500354700002000369700001700389700001300406700001900419700001500438700001700453700001800470700001400488700001200502700001400514700001200528700001100540700001800551700002000569700001700589700001200606700001800618700001400636700001300650700001600663700001700679700001600696700001500712700001300727700001500740856006800755 2014 eng d00aShell and Shape Evolution at N=28: The 40Mg Ground State0 aShell and Shape Evolution at N28 The 40Mg Ground State c04/20140 v801 aCrawford, H.L.1 aFallon, P.1 aMacchiavelli, A.O.1 aClark, R.M.1 aBrown, B., A.1 aTostevin, J.A.1 aBazin, D.1 aAoi, N.1 aDoornenbal, P.1 aMatsushita, M.1 aScheit, H.1 aSteppenbeck, D.1 aTakeuchi, S.1 aBaba, H.1 aCampbell, C.M.1 aCromaz, M.1 aIdeguchi, E.1 aKobayashi, N.1 aKondo, Y.1 aLee, G.1 aLee, I.Y.1 aLee, J.1 aLi, K.1 aMichimasa, S.1 aMotobayashi, T.1 aNakamura, T.1 aOta, S.1 aPaschalis, S.1 aPetri, M.1 aSako, T.1 aSakurai, H.1 aShimoura, S.1 aTakechi, M.1 aTogano, Y.1 aWang, H.1 aYoneda, K. uhttp://journals.aps.org/prc/abstract/10.1103/PhysRevC.89.04130300595nas a2200169 4500008004100000245012700041210006900168260000900237490000800246100001600254700001400270700001500284700001500299700001300314700002000327856007800347 2014 eng d00aUntangling the contributions of image charge and laser profile for optimal photoemission of high-brightness electron beams0 aUntangling the contributions of image charge and laser profile f c20140 v1161 aPortman, J.1 aZhang, H.1 aMakino, K.1 aRuan, C.Y.1 aBerz, M.1 aDuxbury, P., M. uhttp://scitation.aip.org/content/aip/journal/jap/116/17/10.1063/1.490058200727nas a2200181 4500008004100000245016300041210006900204260001200273490000700285100001400292700001800306700001900324700001600343700002200359700002300381700001600404856012500420 2014 eng d00aWRF Model Sensitivity to Land Surface Model and Cumulus Parameterization under Short-Term Climate Extremes over the Southern Great Plains of the United States0 aWRF Model Sensitivity to Land Surface Model and Cumulus Paramete c10/20140 v271 aPei, Lisi1 aMoore, Nathan1 aZhong, Shiyuan1 aLuo, Lifeng1 aHyndman, David, W1 aHeilman, Warren, E1 aGao, Zhiqiu uhttps://icer.msu.edu/research/publications/wrf-model-sensitivity-land-surface-model-cumulus-parameterization-under-short01343nas a2200445 4500008004100000245010100041210006900142260001200211490000800223653001600231653003200247653005600279653002800335653003400363100001500397700001800412700001400430700001900444700001800463700001600481700001500497700001700512700001200529700001200541700001500553700002100568700001800589700001800607700002200625700001500647700001600662700001500678700001400693700001400707700001400721700001100735700001200746700001300758856012600771 2013 eng d00aCLASH: The Enhanced Lensing Efficiency of the Highly Elongated Merging Cluster MACS J0416.1-24030 aCLASH The Enhanced Lensing Efficiency of the Highly Elongated Me c01/20130 v76210adark matter10agalaxies: clusters: general10agalaxies: clusters: individual: MACS J0416.1–240310aGalaxies: High-Redshift10agravitational lensing: strong1 aZitrin, A.1 aMeneghetti, M1 aUmetsu, K1 aBroadhurst, T.1 aBartelmann, M1 aBouwens, R.1 aBradley, L1 aCarrasco, M.1 aCoe, D.1 aFord, H1 aKelson, D.1 aKoekemoer, A., M1 aMedezinski, E1 aMoustakas, J.1 aMoustakas, L., A.1 aNonino, M.1 aPostman, M.1 aRosati, P.1 aSeidel, G1 aSeitz, S.1 aSendra, I1 aShu, X1 aVega, J1 aZheng, W uhttps://icer.msu.edu/research/publications/clash-enhanced-lensing-efficiency-highly-elongated-merging-cluster-macs-j0416101343nas a2200445 4500008004100000245010100041210006900142260001200211490000800223653001600231653003200247653005600279653002800335653003400363100001500397700001800412700001400430700001900444700001800463700001600481700001500497700001700512700001200529700001200541700001500553700002100568700001800589700001800607700002200625700001500647700001600662700001500678700001400693700001400707700001400721700001100735700001200746700001300758856012600771 2013 eng d00aCLASH: The Enhanced Lensing Efficiency of the Highly Elongated Merging Cluster MACS J0416.1-24030 aCLASH The Enhanced Lensing Efficiency of the Highly Elongated Me c01/20130 v76210adark matter10agalaxies: clusters: general10agalaxies: clusters: individual: MACS J0416.1–240310aGalaxies: High-Redshift10agravitational lensing: strong1 aZitrin, A.1 aMeneghetti, M1 aUmetsu, K1 aBroadhurst, T.1 aBartelmann, M1 aBouwens, R.1 aBradley, L1 aCarrasco, M.1 aCoe, D.1 aFord, H1 aKelson, D.1 aKoekemoer, A., M1 aMedezinski, E1 aMoustakas, J.1 aMoustakas, L., A.1 aNonino, M.1 aPostman, M.1 aRosati, P.1 aSeidel, G1 aSeitz, S.1 aSendra, I1 aShu, X1 aVega, J1 aZheng, W uhttps://icer.msu.edu/research/publications/clash-enhanced-lensing-efficiency-highly-elongated-merging-cluster-macs-j041-001273nas a2200433 4500008004100000245006800041210006600109260001200175490000800187653001300195653002800208653001900236653001300255653001500268100001300283700001600296700002300312700001600335700001500351700001800366700001900384700002100403700002100424700002000445700001600465700001400481700002700495700001800522700002000540700002300560700001900583700002200602700002500624700002200649700001800671700002300689700001800712856010900730 2013 eng d00aCLASH: Three Strongly Lensed Images of a Candidate z 11 Galaxy0 aCLASH Three Strongly Lensed Images of a Candidate z 11 Galaxy c01/20130 v76210aclusters10adistances and redshifts10aearly universe10agalaxies10aindividual1 aCoe, Dan1 aZitrin, Adi1 aCarrasco, Mauricio1 aShu, Xinwen1 aZheng, Wei1 aPostman, Marc1 aBradley, Larry1 aKoekemoer, Anton1 aBouwens, Rychard1 aBroadhurst, Tom1 aMonna, Anna1 aHost, Ole1 aMoustakas, Leonidas, A1 aFord, Holland1 aMoustakas, John1 avan der Wel, Arjen1 aDonahue, Megan1 aRodney, Steven, A1 aBen{\'ıtez, Narciso1 aJouvel, Stephanie1 aSeitz, Stella1 aKelson, Daniel, D.1 aRosati, Piero uhttps://icer.msu.edu/research/publications/clash-three-strongly-lensed-images-candidate-z%C2%A011-galaxy01262nas a2200433 4500008004100000245006700041210006500108260001200173490000800185653001300193653002800206653001900234653001300253653001500266100001300281700001600294700002300310700001600333700001500349700001800364700001900382700002100401700002100422700002000443700001600463700001400479700002700493700001800520700002000538700002300558700001900581700002200600700002200622700002200644700001800666700002300684700001800707856010300725 2013 eng d00aCLASH: Three Strongly Lensed Images of a Candidate z~11 Galaxy0 aCLASH Three Strongly Lensed Images of a Candidate z11 Galaxy c01/20130 v76210aclusters10adistances and redshifts10aearly universe10agalaxies10aindividual1 aCoe, Dan1 aZitrin, Adi1 aCarrasco, Mauricio1 aShu, Xinwen1 aZheng, Wei1 aPostman, Marc1 aBradley, Larry1 aKoekemoer, Anton1 aBouwens, Rychard1 aBroadhurst, Tom1 aMonna, Anna1 aHost, Ole1 aMoustakas, Leonidas, A1 aFord, Holland1 aMoustakas, John1 avan der Wel, Arjen1 aDonahue, Megan1 aRodney, Steven, A1 aBenítez, Narciso1 aJouvel, Stephanie1 aSeitz, Stella1 aKelson, Daniel, D.1 aRosati, Piero uhttps://icer.msu.edu/research/publications/clash-three-strongly-lensed-images-candidate-z11-galaxy00555nas a2200121 4500008004100000245012400041210006900165300000600234653002100240100002500261700002100286856012600307 2013 eng d00aEstimating wounding of lake trout by sea lamprey in the upper Great Lakes: Allowing for changing size-specific patterns0 aEstimating wounding of lake trout by sea lamprey in the upper Gr a-10aAD Model Builder1 aPrichard, Carson, G.1 aBence, James, R. uhttps://icer.msu.edu/research/publications/estimating-wounding-lake-trout-sea-lamprey-upper-great-lakes-allowing-changing00482nas a2200109 4500008004100000245008200041210006900123260002500192490000700217100002600224856012200250 2013 eng d00aHeterogeneous relaxation dynamics in amorphous materials under cyclic loading0 aHeterogeneous relaxation dynamics in amorphous materials under c aTampa, FloridabIEEE0 v871 aPriezjev, Nikolai, V. uhttps://icer.msu.edu/research/publications/heterogeneous-relaxation-dynamics-amorphous-materials-under-cyclic-loading01392nas a2200133 4500008004100000245010200041210006900143260002600212520084200238100001701080700001901097700002001116856012201136 2013 eng d00aThe Institute for Cyber-Enabled Research: Regional Organization to Promote Computation in Science0 aInstitute for CyberEnabled Research Regional Organization to Pro aSan Diego, California3 aThe Institute for Cyber-Enabled Research (iCER) at Michigan State University (MSU) was established in 2009 to coordinate and support multidisciplinary resources for computation and computational sciences. iCER is the home of MSU's centralized High Performance Computing resources, which include a heterogeneous compute cluster with various hardware designed to meet the needs of different scientists. The goal of iCER is not to maximize Flops, but instead to maximize the amount of quality science being accomplished. This paper outlines many of the initiatives that iCER has taken to support researchers at MSU and throughout Michigan; describes the structure and evolution of iCER and its relationship with XSEDE and offers insights for other institutions interested in putting together a similar computational organization.

1 aColbry, Dirk1 aPunch, William1 aBauer, Wolfgang uhttps://icer.msu.edu/research/publications/institute-cyber-enabled-research-regional-organization-promote-computation00447nas a2200097 4500008004100000245009400041210006900135490000700204100002000211856011800231 2013 eng d00aMolecular dynamics simulations of oscillatory Couette flows with slip boundary conditions0 aMolecular dynamics simulations of oscillatory Couette flows with0 v141 aPriezjev, N., V uhttps://icer.msu.edu/research/publications/molecular-dynamics-simulations-oscillatory-couette-flows-slip-boundary00557nas a2200133 4500008004100000245011100041210006900152300001400221490000700235100002200242700001800264700001700282856012400299 2012 eng d00aALTITUDINAL CLINAL VARIATION IN WING SIZE AND SHAPE IN AFRICAN DROSOPHILA MELANOGASTER: ONE CLINE OR MANY?0 aALTITUDINAL CLINAL VARIATION IN WING SIZE AND SHAPE IN AFRICAN D a438–4520 v671 aPitchers, William1 aPool, John, E1 aDworkin, Ian uhttps://icer.msu.edu/research/publications/altitudinal-clinal-variation-wing-size-shape-african-drosophila-melanogaster01651nas a2200553 4500008004100000245022000041210006900261260001200330653006000342100001500402700001500417700001500432700001200447700001400459700001300473700001200486700001300498700001600511700001700527700001300544700001700557700001500574700001500589700001800604700001800622700001200640700001500652700001300667700001400680700001900694700001800713700001500731700001800746700001200764700001500776700001500791700001500806700002000821700001400841700001400855700001200869700001800881700001600899700001400915700001500929700001300944700001400957856012600971 2012 eng d00aA Census of Star-Forming Galaxies in the z~9-10 Universe based on HST+Spitzer Observations Over 19 CLASH clusters: Three Candidate z~9-10 Galaxies and Improved Constraints on the Star Formation Rate Density at z~9.20 aCensus of StarForming Galaxies in the z910 Universe based on HST c11/201210aAstrophysics - Cosmology and Extragalactic Astrophysics1 aBouwens, R1 aBradley, L1 aZitrin, A.1 aCoe, D.1 aFranx, M.1 aZheng, W1 aSmit, R1 aHost, O.1 aPostman, M.1 aMoustakas, L1 aLabbe, I1 aCarrasco, M.1 aMolino, A.1 aDonahue, M1 aKelson, D., D1 aMeneghetti, M1 aJha, S.1 aBenitez, N1 aLemze, D1 aUmetsu, K1 aBroadhurst, T.1 aMoustakas, J.1 aRosati, P.1 aBartelmann, M1 aFord, H1 aGraves, G.1 aGrillo, C.1 aInfante, L1 aJiminez-Teja, Y1 aJouvel, S1 aLahav, O.1 aMaoz, D1 aMedezinski, E1 aMelchior, P1 aMerten, J1 aNonino, M.1 aOgaz, S.1 aSeitz, S. uhttps://icer.msu.edu/research/publications/census-star-forming-galaxies-z9-10-universe-based-hstspitzer-observations-over01350nas a2200457 4500008004100000245009300041210006900134260001200203490000800215653001600223653003200239653005400271653002800325653003400353100001500387700001800402700001500420700001200435700002200447700001600469700001100485700001300496700001700509700001600526700001900542700001200561700001300573700001400586700001800600700001800618700001500636700001500651700001500666700001500681700001300696700001800709700001500727700001500742700001300757856012200770 2012 eng d00aCLASH: Discovery of a Bright z ~= 6.2 Dwarf Galaxy Quadruply Lensed by MACS J0329.6-02110 aCLASH Discovery of a Bright z 62 Dwarf Galaxy Quadruply Lensed b c03/20120 v74710adark matter10agalaxies: clusters: general10agalaxies: clusters: individual: MACS J0329.6-021110aGalaxies: High-Redshift10agravitational lensing: strong1 aZitrin, A.1 aMoustakas, J.1 aBradley, L1 aCoe, D.1 aMoustakas, L., A.1 aPostman, M.1 aShu, X1 aZheng, W1 aBenítez, N.1 aBouwens, R.1 aBroadhurst, T.1 aFord, H1 aHost, O.1 aJouvel, S1 aKoekemoer, A.1 aMeneghetti, M1 aRosati, P.1 aDonahue, M1 aGrillo, C.1 aKelson, D.1 aLemze, D1 aMedezinski, E1 aMolino, A.1 aNonino, M.1 aOgaz, S. uhttps://icer.msu.edu/research/publications/clash-discovery-bright-z-62-dwarf-galaxy-quadruply-lensed-macs-j03296-021102193nas a2200733 4500008004100000245009800041210006900139260001200208490000800220653002800228653001600256653005400272653003400326653003200360100002000392700002300412700001800435700001900453700001600472700002000488700002000508700002300528700001900551700002200570700001300592700001800605700002100623700001900644700001700663700002200680700001900702700002100721700001800742700002200760700001800782700002000800700002000820700002100840700002000861700001800881700002200899700001900921700001800940700002200958700001400980700001700994700002001011700002401031700002401055700002501079700002201104700002101126700001901147700001801166700002701184700001901211700001601230700002001246700002001266700001501286700001801301700001501319856012501334 2012 eng d00aCLASH: Mass Distribution in and around MACS J1206.2-0847 from a Full Cluster Lensing Analysis0 aCLASH Mass Distribution in and around MACS J120620847 from a Ful c08/20120 v75510acosmology: observations10adark matter10agalaxies: clusters: individual: MACS J1206.2-084710agravitational lensing: strong10agravitational lensing: weak1 aUmetsu, Keiichi1 aMedezinski, Elinor1 aNonino, Mario1 aMerten, Julian1 aZitrin, Adi1 aMolino, Alberto1 aGrillo, Claudio1 aCarrasco, Mauricio1 aDonahue, Megan1 aMahdavi, Andisheh1 aCoe, Dan1 aPostman, Marc1 aKoekemoer, Anton1 aCzakon, Nicole1 aSayers, Jack1 aMroczkowski, Tony1 aGolwala, Sunil1 aKoch, Patrick, M1 aLin, Kai-Yang1 aMolnar, Sandor, M1 aRosati, Piero1 aBalestra, Italo1 aMercurio, Amata1 aScodeggio, Marco1 aBiviano, Andrea1 aAnguita, Timo1 aInfante, Leopoldo1 aSeidel, Gregor1 aSendra, Irene1 aJouvel, Stephanie1 aHost, Ole1 aLemze, Doron1 aBroadhurst, Tom1 aMeneghetti, Massimo1 aMoustakas, Leonidas1 aBartelmann, Matthias1 aBenítez, Narciso1 aBouwens, Rychard1 aBradley, Larry1 aFord, Holland1 aJiménez-Teja, Yolanda1 aKelson, Daniel1 aLahav, Ofer1 aMelchior, Peter1 aMoustakas, John1 aOgaz, Sara1 aSeitz, Stella1 aZheng, Wei uhttps://icer.msu.edu/research/publications/clash-mass-distribution-around-macs-j12062-0847-full-cluster-lensing-analysis01974nas a2200733 4500008004100000245008800041210006900129260001200198490000800210653001600218653003200234653005600266653002800322653003400350100001500384700001500399700001500414700001500429700001600444700001200460700001400472700001500486700001900501700001400520700001700534700001600551700001700567700001700584700001500601700001200616700001300628700002000641700001800661700001300679700001800692700001600710700001400726700001500740700001300755700001500768700001500783700001200798700001500810700001400825700001400839700001300853700001700866700001200883700001600895700001800911700001600929700001800945700001400963700001500977700002200992700001301014700001401027700001501041700001401056700001401070700001401084700002001098856012201118 2012 eng d00aCLASH: New Multiple Images Constraining the Inner Mass Profile of MACS J1206.2-08470 aCLASH New Multiple Images Constraining the Inner Mass Profile of c04/20120 v74910adark matter10agalaxies: clusters: general10agalaxies: clusters: individual: MACS J1206.2–084710aGalaxies: High-Redshift10agravitational lensing: strong1 aZitrin, A.1 aRosati, P.1 aNonino, M.1 aGrillo, C.1 aPostman, M.1 aCoe, D.1 aSeitz, S.1 aEichner, T1 aBroadhurst, T.1 aJouvel, S1 aBalestra, I.1 aMercurio, A1 aScodeggio, M1 aBenítez, N.1 aBradley, L1 aFord, H1 aHost, O.1 aJimenez-Teja, Y1 aKoekemoer, A.1 aZheng, W1 aBartelmann, M1 aBouwens, R.1 aCzoske, O1 aDonahue, M1 aGraur, O1 aGraves, G.1 aInfante, L1 aJha, S.1 aKelson, D.1 aLahav, O.1 aLazkoz, R1 aLemze, D1 aLombardi, M.1 aMaoz, D1 aMcCully, C.1 aMedezinski, E1 aMelchior, P1 aMeneghetti, M1 aMerten, J1 aMolino, A.1 aMoustakas, L., A.1 aOgaz, S.1 aPatel, B.1 aRegoes, E.1 aRiess, A.1 aRodney, S1 aUmetsu, K1 aVan der Wel, A. uhttps://icer.msu.edu/research/publications/clash-new-multiple-images-constraining-inner-mass-profile-macs-j12062-084701835nas a2200637 4500008004100000245007600041210006900117260001200186490000800198100001300206700002000219700001600239700001900255700002300274700001800297700002300315700001800338700002400356700002300380700002400403700002200427700001900449700002100468700001500489700001800504700002000522700002200542700001700564700002200581700001500603700002000618700001400638700001800652700002000670700001800690700002700708700002000735700002000755700001700775700002500792700002200817700002100839700001400860700002200874700001600896700002200912700001900934700002400953700001400977700002400991700001901015700001601034700001801050700001801068856011101086 2012 eng d00aCLASH: Precise New Constraints on the Mass Profile Galaxy Cluster A22610 aCLASH Precise New Constraints on the Mass Profile Galaxy Cluster c09/20120 v7571 aCoe, Dan1 aUmetsu, Keiichi1 aZitrin, Adi1 aDonahue, Megan1 aMedezinski, Elinor1 aPostman, Marc1 aCarrasco, Mauricio1 aAnguita, Timo1 aGeller, Margaret, J1 aRines, Kenneth, J.1 aDiaferio, Antonaldo1 aKurtz, Michael, J1 aBradley, Larry1 aKoekemoer, Anton1 aZheng, Wei1 aNonino, Mario1 aMolino, Alberto1 aMahdavi, Andisheh1 aLemze, Doron1 aInfante, Leopoldo1 aOgaz, Sara1 aMelchior, Peter1 aHost, Ole1 aFord, Holland1 aGrillo, Claudio1 aRosati, Piero1 aJiménez-Teja, Yolanda1 aMoustakas, John1 aAscaso, Begoña1 aLahav, Ofer;1 aBartelmann, Matthias1 aBenítez, Narciso1 aBouwens, Rychard1 aGraur, Or1 aGraves, Genevieve1 aJha, Saurab1 aJouvel, Stephanie1 aKelson, Daniel1 aMoustakas, Leonidas1 aMaoz, Dan1 aMeneghetti, Massimo1 aMerten, Julian1 aRiess, Adam1 aRodney, Steve1 aSeitz, Stella uhttps://icer.msu.edu/research/publications/clash-precise-new-constraints-mass-profile-galaxy-cluster-a226100580nas a2200145 4500008004100000245009200041210006900133260003500202300001100237490000800248100001600256700002200272700002000294856012000314 2012 eng d00aDesigning Electrical Contacts to ${\mathrm{MoS}}_{2}$ Monolayers: A Computational Study0 aDesigning Electrical Contacts to mathrm MoS 2 Monolayers A Compu bAmerican Physical SocietycApr a1568020 v1081 aPopov, Igor1 aSeifert, Gotthard1 aTománek, David uhttps://icer.msu.edu/research/publications/designing-electrical-contacts-mathrmmos-2-monolayers-computational-study00486nas a2200133 4500008004100000245006700041210006700108300001400175490000700189100001900196700002100215700001300236856010300249 2012 eng d00aDynamics of Performing and Remembering Organizational Routines0 aDynamics of Performing and Remembering Organizational Routines a1536-15580 v491 aMiller, K., D.1 aPentland, B., T.1 aChoi, S. uhttps://icer.msu.edu/research/publications/dynamics-performing-remembering-organizational-routines00531nas a2200121 4500008004100000245010600041210006900147260001200216490000800228100002400236700002600260856012300286 2012 eng d00aEffects of crossflow velocity and transmembrane pressure on microfiltration of oil-in-water emulsions0 aEffects of crossflow velocity and transmembrane pressure on micr c10/20120 v4231 aDarvishzadeh, Tohid1 aPriezjev, Nikolai, V. uhttps://icer.msu.edu/research/publications/effects-crossflow-velocity-transmembrane-pressure-microfiltration-oil-water00441nas a2200097 4500008004100000245008000041210006900121490000800190100002600198856011900224 2012 eng d00aInterfacial friction between semiflexible polymers and crystalline surfaces0 aInterfacial friction between semiflexible polymers and crystalli0 v1361 aPriezjev, Nikolai, V. uhttps://icer.msu.edu/research/publications/interfacial-friction-between-semiflexible-polymers-crystalline-surfaces01554nas a2200529 4500008004100000245007700041210006900118260001200187490000800199100001500207700001800222700001600240700002000256700001600276700002200292700001500314700002000329700001900349700001300368700002700381700002300408700001800431700002200449700001800471700002200489700002100511700002100532700002300553700002500576700002000601700001900621700002000640700002200660700002000682700002300702700001600725700001700741700002000758700002400778700001900802700001800821700001500839700001800854700002000872700002300892856010900915 2012 eng d00aA magnified young galaxy from about 500 million years after the Big Bang0 amagnified young galaxy from about 500 million years after the Bi c09/20120 v4891 aZheng, Wei1 aPostman, Marc1 aZitrin, Adi1 aMoustakas, John1 aShu, Xinwen1 aJouvel, Stephanie1 aHøst, Ole1 aMolino, Alberto1 aBradley, Larry1 aCoe, Dan1 aMoustakas, Leonidas, A1 aCarrasco, Mauricio1 aFord, Holland1 aBenítez, Narciso1 aLauer, Tod, R1 aSeitz, Stella;, B1 aBouwens, Rychard1 aKoekemoer, Anton1 aMedezinski, Elinor1 aBartelmann, Matthias1 aBroadhurst, Tom1 aDonahue, Megan1 aGrillo, Claudio1 aInfante, Leopoldo1 aJha, Saurabh, W1 aKelson, Daniel, D.1 aLahav, Ofer1 aLemze, Doron1 aMelchior, Peter1 aMeneghetti, Massimo1 aMerten, Julian1 aNonino, Mario1 aOgaz, Sara1 aRosati, Piero1 aUmetsu, Keiichi1 avan der Wel, Arjen uhttps://icer.msu.edu/research/publications/magnified-young-galaxy-about-500-million-years-after-big-bang00670nas a2200169 4500008004100000245011800041210006900159100002100228700002200249700001700271700001400288700001700302700001600319700002200335700001800357856012500375 2011 eng d00aThe Comprehensive Phytopathogen Genomics Resource: An electronic resource for data-mining plant pathogen genomes0 aComprehensive Phytopathogen Genomics Resource An electronic reso1 aHamilton, J., P.1 aNeeno-Eckwall, E.1 aAdhikari, B.1 aPerna, N.1 aTisserat, N.1 aLeach, J.E.1 aLévesque, C., A.1 aBuell, C., R. uhttps://icer.msu.edu/research/publications/comprehensive-phytopathogen-genomics-resource-electronic-resource-data-mining00693nas a2200181 4500008004100000245011800041210006900159490000800228100001800236700002300254700002200277700001900299700001900318700002000337700001600357700001500373856012300388 2011 eng d00aEast African Food Security as Influenced by Future Climate Change and Land Use Change at Local to Regional Scales0 aEast African Food Security as Influenced by Future Climate Chang0 v1071 aMoore, Nathan1 aAlagarswamy, Gopal1 aPijanowski, Bryan1 aThornton, Phil1 aLofgren, Brent1 aOlson, Jennifer1 aYanda, Pius1 aQi, Jiaguo uhttps://icer.msu.edu/research/publications/east-african-food-security-influenced-future-climate-change-land-use-change00500nas a2200133 4500008004100000245006700041210006600108490000700174100002200181700001800203700002200221700001600243856010700259 2011 eng d00aEvaluating error propagation in coupled land-atmosphere models0 aEvaluating error propagation in coupled landatmosphere models0 v151 aPijanowski, Bryan1 aMoore, Nathan1 aMauree, Desaraden1 aNiyogi, Dev uhttps://icer.msu.edu/research/publications/evaluating-error-propagation-coupled-land-atmosphere-models00476nas a2200097 4500008004100000245011600041210006900157490000800226100002000234856012400254 2011 eng d00aMolecular diffusion and slip boundary conditions at smooth surfaces with periodic and random nanoscale textures0 aMolecular diffusion and slip boundary conditions at smooth surfa0 v1351 aPriezjev, N., V uhttps://icer.msu.edu/research/publications/molecular-diffusion-slip-boundary-conditions-smooth-surfaces-periodic-random00480nas a2200121 4500008004100000245007900041210006900120100001400189700001800203700001800221700001400239856010500253 2011 eng d00aOn the Performance of Indirect Encoding Across the Continuum of Regularity0 aPerformance of Indirect Encoding Across the Continuum of Regular1 aClune, J.1 aStanley, K.O.1 aPennock, R.T.1 aOfria, C. uhttps://icer.msu.edu/research/publications/performance-indirect-encoding-across-continuum-regularity00643nas a2200157 4500008004100000245014700041210006900188260002200257300001200279490000800291100001400299700001800313700001400331700001800345856012200363 2011 eng d00aSelective pressures for accurate altruism targeting: evidence from digital evolution for difficult-to-test aspects of inclusive fitness theory0 aSelective pressures for accurate altruism targeting evidence fro bThe Royal Society a666-6740 v2781 aClune, J.1 aGoldsby, H.J.1 aOfria, C.1 aPennock, R.T. uhttps://icer.msu.edu/research/publications/selective-pressures-accurate-altruism-targeting-evidence-digital-evolution00656nas a2200181 4500008004100000245008800041210006900129490000700198100001800205700002000223700002200243700002000265700001500285700001800300700002200318700002000340856011400360 2010 eng d00aAdapting MODIS-derived LAI and fractional cover into the RAMS model for East Africa0 aAdapting MODISderived LAI and fractional cover into the RAMS mod0 v301 aMoore, Nathan1 aTorbick, Nathan1 aPijanowski, Bryan1 aLofrgren, Brent1 aWang, Jing1 aKim, Dong-Yun1 aAndresen, Jeffrey1 aOlson, Jennifer uhttps://icer.msu.edu/research/publications/adapting-modis-derived-lai-fractional-cover-rams-model-east-africa01865nas a2200145 4500008004100000245012500041210006900166260001200235300001400247490000800261520129200269100001701561700001801578856012301596 2010 eng d00aConformational Sampling of Influenza Fusion Peptide in Membrane Bilayers as a Function of Termini and Protonation States0 aConformational Sampling of Influenza Fusion Peptide in Membrane c12/2009 a1407-14160 v1143 aInfluenza fusion peptide is critical for mediating the fusion of viral and host cell membranes during viral entry. The interaction of monomeric influenza fusion peptide with membranes is studied with replica exchange molecular dynamics simulations using a new implicit membrane model to effectively reach microsecond to millisecond time scales. The conformational sampling of the fusion peptide was studied as a function of different N- and C-termini, including an experimental construct with an additional C-terminal tag, as well as a function of protonation of acidic residues. It is found that the influenza fusion peptide mostly adopts helical structures with a pronounced kink at residues 11−13 with both N-terminal and C-terminal helices oriented mostly parallel to the membrane surface. A charged C-terminus and the presence of a charge C-terminal tag significantly alters the conformational sampling of the fusion peptide and results in more diverse conformational ensembles that include obliquely inserted N-terminal peptide structures. Protonation of acidic residues also affects the conformational sampling, however, based on pKa shift estimates the overall effect of pH = 5 on the conformational sampling of the influenza fusion peptide appears to be only minor.

1 aPanahi, Afra1 aFeig, Michael uhttps://icer.msu.edu/research/publications/conformational-sampling-influenza-fusion-peptide-membrane-bilayers-function01985nas a2200133 4500008004100000245009900041210006900140260001200209490000700221520146000228100001801688700002001706856012501726 2010 eng d00aModeling the combined effect of surface roughness and shear rate on slip flow of simple fluids0 aModeling the combined effect of surface roughness and shear rate c01/20100 v813 aMolecular dynamics (MD) and continuum simulations are carried out to investigate the influence of shear rate and surface roughness on slip flow of a Newtonian fluid. For weak wall-fluid interaction energy, the nonlinear shear-rate dependence of the intrinsic slip length in the flow over an atomically flat surface is computed by MD simulations. We describe laminar flow away from a curved boundary by means of the effective slip length defined with respect to the mean height of the surface roughness. Both the magnitude of the effective slip length and the slope of its rate dependence are significantly reduced in the presence of periodic surface roughness. We then numerically solve the Navier-Stokes equation for the flow over the rough surface using the rate-dependent intrinsic slip length as a local boundary condition. Continuum simulations reproduce the behavior of the effective slip length obtained from MD simulations at low shear rates. The slight discrepancy between MD and continuum results at high shear rates is explained by examination of the local velocity profiles and the pressure distribution along the wavy surface. We found that in the region where the curved boundary faces the mainstream flow, the local slip is suppressed due to the increase in pressure. The results of the comparative analysis can potentially lead to the development of an efficient algorithm for modeling rate-dependent slip flows over rough surfaces.

1 aNiavarani, A.1 aPriezjev, N., V uhttps://icer.msu.edu/research/publications/modeling-combined-effect-surface-roughness-shear-rate-slip-flow-simple-fluids01728nas a2200145 4500008004100000245014900041210006900190260001200259300001400271490000800285520113400293100001201427700001901439856012401458 2010 eng d00aMulti-level Extension of the Cluster-In-Molecule Local Correlation Methodology: Merging Coupled-Cluster and Moller-Plesset Perturbation Theories0 aMultilevel Extension of the ClusterInMolecule Local Correlation c05/2010 a6721-67270 v1143 aA multilevel extension of the local correlation “cluster-in-molecule” (CIM) framework, which enables one to combine different quantum chemistry methods to treat different regions in a large molecular system without splitting it into ad hoc fragments and saturating dangling bonds, is proposed. The resulting schemes combine higher-level methods, such as the completely renormalized coupled-cluster (CC) approach with singles, doubles, and noniterative triples, termed CR-CC(2,3), to treat the reactive part of a large molecular system, and lower-order methods, such as the second-order Møller−Plesset perturbation theory (MP2), to handle the chemically inactive regions. The multilevel CIM-CC/MP2 approaches preserve the key features of all CIM methods, such as the use of orthonormal localized orbitals and coarse-grain parallelism, while substantially reducing the already relatively low costs of the single-level CIM-CC calculations. Illustrative calculations include bond breaking in dodecane and the reactions of the bis(2,4,4-trimethylpentyl)dithiophosphinic acid with one and two water molecules.

1 aLi, Wei1 aPiecuch, Piotr uhttps://icer.msu.edu/research/publications/multi-level-extension-cluster-molecule-local-correlation-methodology-merging02260nas a2200133 4500008004100000245014300041210006900184260001200253490000700265520169300272100001901965700001901984856012302003 2010 eng d00aA Process-Based, Distributed Hydrologic Model Based on a Large-Scale Method for Surface - Subsurface Coupling, Advances in Water Resources0 aProcessBased Distributed Hydrologic Model Based on a LargeScale c09/20100 v333 aProcess-based watershed models are useful tools for understanding the impacts of natural and anthropogenic influences on water resources and for predicting water and solute fluxes exported from watersheds to receiving water bodies. The applicability of process-based hydrologic models has been previously limited to small catchments and short time frames. Computational demands, especially the solution to the three-dimensional subsurface flow domain, continue to pose significant constraints. This paper documents the mathematical development, numerical testing and the initial application of a new distributed hydrologic model PAWS (Process-based Adaptive Watershed Simulator). The model solves the governing equations for the major hydrologic processes efficiently so that large scale applications become relevant. PAWS evaluates the integrated hydrologic response of the surface–subsurface system using a novel non-iterative method that couples runoff and groundwater flow to vadose zone processes approximating the 3D Richards equation. The method is computationally efficient and produces physically consistent solutions. All flow components have been independently verified using analytical solutions and experimental data where applicable. The model is applied to a medium-sized watershed in Michigan (1169 km2) achieving high performance metrics in terms of streamflow prediction at two gages during the calibration and verification periods. PAWS uses public databases as input and possesses full capability to interact with GIS datasets. Future papers will describe applications to other watersheds and the development and application of fate and transport modules.

1 aShen, Chaopeng1 aPhanikumar, M. uhttps://icer.msu.edu/research/publications/process-based-distributed-hydrologic-model-based-large-scale-method-surface00453nas a2200097 4500008004100000245009400041210006900135490000700204100002000211856012400231 2010 eng d00aRelationship between induced fluid structure and boundary slip in nanoscale polymer films0 aRelationship between induced fluid structure and boundary slip i0 v821 aPriezjev, N., V uhttps://icer.msu.edu/research/publications/relationship-between-induced-fluid-structure-boundary-slip-nanoscale-polymer00512nas a2200133 4500008004100000245008700041210006900128260001200197490000700209100000500216700001600221700001900237856012200256 2009 eng d00aAb Initio Coupled-Cluster and Configuration Interaction Calculations for O Using V0 aAb Initio CoupledCluster and Configuration Interaction Calculati c05/20090 v791 a1 aGour, J., R1 aPiecuch, Piotr uhttps://icer.msu.edu/research/publications/ab-initio-coupled-cluster-configuration-interaction-calculations-o-using-v01184nas a2200157 4500008004100000245009900041210006900140260001200209300001200221490000800233520062000241100000500861700002200866700001900888856011900907 2009 eng d00aCenter-of-Mass Problem in Truncated Configuration Interaction and Coupled-Cluster Calculations0 aCenterofMass Problem in Truncated Configuration Interaction and c08/2009 a334-3390 v6793 aThe problem of center-of-mass (CM) contaminations in ab initio nuclear structure calculations using configuration interaction (CI) and coupled-cluster (CC) approaches is analyzed. A rigorous and quantitative scheme for diagnosing the CM contamination of intrinsic observables is proposed and applied to ground-state calculations for 4He and 16O. The CI and CC calculations for 16O based on model spaces defined via a truncation of the single-particle basis lead to sizable CM contaminations, while the importance-truncated no-core shell model based on the NmaxΩ space is virtually free of CM contaminations.

1 a1 aGour, Jeffrey, R.1 aPiecuch, Piotr uhttps://icer.msu.edu/research/publications/center-mass-problem-truncated-configuration-interaction-coupled-cluster01895nas a2200217 4500008004100000245008800041210006900129260001200198490000700210520117900217653001901396653001701415653002801432653001901460653001501479653001401494653001301508100001801521700002001539856011801559 2009 eng d00aThe effective slip length and vortex formation in laminar flow over a rough surface0 aeffective slip length and vortex formation in laminar flow over c05/20090 v213 aThe flow of viscous incompressible fluid over a periodically corrugated surface is investigated numerically by solving the Navier–Stokes equation with the local slip and no-slip boundary conditions. We consider the effective slip length which is defined with respect to the level of the mean height of the surface roughness. With increasing corrugation amplitude the effective no-slip boundary plane is shifted toward the bulk of the fluid, which implies a negative effective slip length. The analysis of the wall shear stress indicates that a flow circulation is developed in the grooves of the rough surface provided that the local boundary condition is no-slip. By applying a local slip boundary condition, the center of the vortex is displaced toward the bottom of the grooves and the effective slip length increases. When the intrinsic slip length is larger than the corrugation amplitude, the flow streamlines near the surface are deformed to follow the boundary curvature, the vortex vanishes, and the effective slip length saturates to a constant value. Inertial effects promote vortex flow formation in the grooves and reduce the effective slip length.

10aexternal flows10alaminar flow10aNavier-Stokes equations10arough surfaces10ashear flow10aslip flow10avortices1 aNiavarani, A.1 aPriezjev, N., V uhttps://icer.msu.edu/research/publications/effective-slip-length-vortex-formation-laminar-flow-over-rough-surface00517nas a2200133 4500008004100000245008000041210006900121300001400190100001400204700001900218700001400237700001800251856011400269 2009 eng d00aEvolving coordinated quadruped gaits with the HyperNEAT generative encoding0 aEvolving coordinated quadruped gaits with the HyperNEAT generati a2764-27711 aClune, J.1 aBeckmann, B.E.1 aOfria, C.1 aPennock, R.T. uhttps://icer.msu.edu/research/publications/evolving-coordinated-quadruped-gaits-hyperneat-generative-encoding00506nas a2200121 4500008004100000245009000041210006900131100001400200700001900214700001800233700001400251856011900265 2009 eng d00aHybrID: A Hybridization of Indirect and Direct Encodings for Evolutionary Computation0 aHybrID A Hybridization of Indirect and Direct Encodings for Evol1 aClune, J.1 aBeckmann, B.E.1 aPennock, R.T.1 aOfria, C. uhttps://icer.msu.edu/research/publications/hybrid-hybridization-indirect-direct-encodings-evolutionary-computation02843nas a2200157 4500008004100000245022400041210006900265260001200334300001400346490000800360520214900368100001902517700001602536700001402552856011902566 2009 eng d00aLeft-Eigenstate Completely Renormalized Equation-of-motion Coupled-Cluster Methods: Review of Key Concepts, Extension to Excited States of Open-Shell Systems, and Comparison with Electron-Attached and ionized Approaches0 aLeftEigenstate Completely Renormalized Equationofmotion CoupledC c11/2009 a3268-33040 v1093 aThe recently proposed left-eigenstate completely renormalized (CR) coupled-cluster (CC) method with singles, doubles, and noniterative triples, termed CR-CC(2,3) Piecuch and Włoch, J Chem Phys, 2005, 123, 224105; Piecuch et al. Chem Phys Lett, 2006, 418, 467 and the companion CR-EOMCC(2,3) methodology, which has been previously applied to singlet excited states of closed-shell molecular systems Włoch et al. Mol Phys, 2006, 104, 2149 and in which relatively inexpensive noniterative corrections due to triple excitations derived from the biorthogonal method of moments of CC equations (MMCC) are added to the CC singles and doubles (CCSD) or equation-of-motion (EOM) CCSD energies, have been extended to excited states of open-shell species. The resulting highly efficient computer codes for the open-shell CR-EOMCC(2,3) approach exploiting the recursively generated intermediates and fast matrix multiplication routines have been developed and interfaced with the GAMESS package, enabling CR-EOMCC(2,3) calculations for singlet as well as nonsinglet ground and excited states of closed- and open-shell systems using the restricted Hartree–Fock or restricted open-shell Hartree–Fock references. A number of important mathematical and algorithmic details related to formal aspects and computer implementation of the CR-EOMCC(2,3) method have been discussed, in addition to overviewing the key concepts behind the CR-EOMCC(2,3) and biorthogonal MMCC methodologies for ground and excited states, and the numerical results involving low-lying states of the CH, CNC, C2N, N3, and NCO species, including states dominated by two-electron transitions, have been presented. The results of the CR-EOMCC(2,3) calculations have been compared with other CC/EOMCC approaches, including the EOMCCSD and EOMCC singles, doubles, and triples methods, and their full and active-space valence counterparts based on the electron-attached and ionized EOMCC methodologies, and the predecessor of CR-EOMCC(2,3) termed CR-EOMCCSD(T) Kowalski and Piecuch, J Chem Phys, 2004, 120, 1715. © 2009 Wiley Periodicals, Inc. Int J Quantum Chem, 2009

1 aPiecuch, Piotr1 aGour, J., R1 aWloch, M. uhttps://icer.msu.edu/research/publications/left-eigenstate-completely-renormalized-equation-motion-coupled-cluster01687nas a2200157 4500008004100000245009400041210006900135260001200204490000800216520112100224100001201345700001901357700001601376700001501392856012201407 2009 eng d00aLocal Correlation Calculations Using Standard and Renormalized Coupled-Cluster Approaches0 aLocal Correlation Calculations Using Standard and Renormalized C c09/20090 v1313 ahe linear scaling local correlation approach, termed “cluster-in-molecule” (CIM), is extended to the coupled-cluster (CC) theory with singles and doubles (CCSD) and CC methods with singles, doubles, and noniterative triples, including CCSD(T) and the completely renormalized CR-CC(2,3) approach. The resulting CIM-CCSD, CIM-CCSD(T), and CIM-CR-CC(2,3) methods are characterized by (i) the linear scaling of the CPU time with the system size, (ii) the use of orthonormal orbitals in the CC subsystem calculations, (iii) the natural parallelism, (iv) the high computational efficiency, enabling calculations for much larger systems and at higher levels of CC theory than previously possible, and (v) the purely noniterative character of local triples corrections. By comparing the results of the canonical and CIM-CC calculations for normal alkanes and water clusters, it is shown that the CIM-CCSD, CIM-CCSD(T), and CIM-CR-CC(2,3) approaches accurately reproduce the corresponding canonical CC correlation and relative energies, while offering savings in the computer effort by orders of magnitude.

1 aLi, Wei1 aPiecuch, Piotr1 aGour, J., R1 aLi, Shuhua uhttps://icer.msu.edu/research/publications/local-correlation-calculations-using-standard-renormalized-coupled-cluster02324nas a2200157 4500008004100000245021700041210007300258260001200331300001200343490000800355520162000363100001401983700001601997700001902013856013402032 2009 eng d00aLow-Lying Valence Excited States of CNC, C₂N, N₃ and NCO Studied Using the Electron-Attached and Ionized Symmetry-Adapted Cluster Configuration-Interaction and Equation-of-Motion Coupled-Cluster Methodologies0 aLowLying Valence Excited States of CNC C₂N N₃ and NCO Studied Us c04/2009 a871-8800 v1073 aLow-lying valence excited states of four open-shell triatomic molecules, CNC, C2N, N3, and NCO, are investigated using the electron-attached (EA) and ionized (IP) symmetry-adapted-cluster configuration-interaction (SAC-CI) general-R as well as the full and active-space EA and IP equation-of-motion coupled-cluster (EOMCC) methods. A comparison is made with experiment and with the results of the completely renormalized (CR) CC calculations with singles, doubles, and non-iterative triples defining the CR-CC(2,3) approach. Adiabatic excitation energies of the calculated states are in reasonable agreement with the experimental values, provided that the 3-particle-2-hole (3p-2h) components in the electron attaching operator, as in the EA SAC-CI SDT-R and EA EOMCCSD(3p-2h) approaches, are included in the calculations for the excited states of C2N and CNC which have a predominantly two-electron character. The results also reveal that the active-space EA/IP EOMCC schemes with up to 3p-2h/3h-2p excitations are able to accurately reproduce the results of their much more expensive parent methods while requiring significantly less computational effort. Furthermore, the more 'black-box' CR-CC(2,3) approach calculates the lowest state of each symmetry with the same accuracy as that obtained with the EA/IP SAC-CI SDT-R and EA/IP EOMCCSD(3p-2h/3h-2p) methods, confirming the significance of higher-order correlation effects in obtaining an accurate description of excited states of radicals, particularly the valence excited states of the CNC and C2N species dominated by two-electron processes.

1 aEhara, M.1 aGour, J., R1 aPiecuch, Piotr uhttps://icer.msu.edu/research/publications/low-lying-valence-excited-states-cnc-c%E2%82%82n-n%E2%82%83-nco-studied-using-electron01793nas a2200145 4500008004100000245015600041210006900197260001200266300001400278490000800292520118900300100001601489700001901505856012301524 2009 eng d00aMethod of Moments for the Continuous Transition Between the Brillouin-Wigner-Type and Rayleigh-Schrodinger-Type Multireference Coupled Cluster Theories0 aMethod of Moments for the Continuous Transition Between the Bril c01/2009 a1209-12210 v1073 aWe apply the method of moments to the multireference (MR) coupled cluster (CC) formalism representing the continuous transition between the Brillouin-Wigner-type and Rayleigh-Schr\"{o}dinger-type theories based on the Jeziorski-Monkhorst wave function ansatz and derive the formula for the noniterative energy corrections to the corresponding MRCC energies that recover the exact, full configuration interaction energies in the general model space case, including complete and incomplete model spaces. We also extend the relationship between the generalized moments of the state-universal (SU) MRCC equations within the Jeziorski-Monkhorst and Kucharski-Bartlett formulations of the SUMRCC theory to the general model space case. Finally, we argue that in the complete model space case, the relationship between moments of the SUMRCC equations corresponding to the Jeziorski-Monkhorst and Kucharski-Bartlett formulations of the SUMRCC theory, derived in this work, implies an equivalence of these two formulations of the SUMRCC approach, provided that the disconnected linked terms are included in the Kucharski-Bartlett formulation, and verify this statement numerically.

1 aPittner, J.1 aPiecuch, Piotr uhttps://icer.msu.edu/research/publications/method-moments-continuous-transition-between-brillouin-wigner-type-rayleigh00586nas a2200193 4500008004100000245004700041210004700088260001200135490000800147100001900155700001800174700001900192700001800211700002100229700002200250700001900272700002000291856008100311 2009 eng d00aProtecting the Amazon with Protected Areas0 aProtecting the Amazon with Protected Areas c08/20090 v1061 aWalker, Robert1 aMoore, Nathan1 aArima, Eugenio1 aPerz, Stephen1 aSimmons, Cynthia1 aCaldas, Marcellus1 aVergara, Dante1 aBohrer, Claudio uhttps://icer.msu.edu/research/publications/protecting-amazon-protected-areas00490nas a2200121 4500008004100000245008500041210006900126300001400195100001400209700001400223700001800237856011300255 2009 eng d00aThe sensitivity of HyperNEAT to different geometric representations of a problem0 asensitivity of HyperNEAT to different geometric representations a675–6821 aClune, J.1 aOfria, C.1 aPennock, R.T. uhttps://icer.msu.edu/research/publications/sensitivity-hyperneat-different-geometric-representations-problem01699nas a2200133 4500008004100000245007000041210006900111260001200180300001300192490000700205520123100212100002001443856010201463 2009 eng d00aShear rate threshold for the boundary slip in dense polymer films0 aShear rate threshold for the boundary slip in dense polymer film c09/2009 a11 Pages0 v803 aThe shear rate dependence of the slip length in thin polymer films confined between atomically flat surfaces is investigated by molecular dynamics simulations. The polymer melt is described by the bead-spring model of linear flexible chains. We found that at low shear rates the velocity profiles acquire a pronounced curvature near the wall and the absolute value of the negative slip length is approximately equal to the thickness of the viscous interfacial layer. At higher shear rates, the velocity profiles become linear and the slip length increases rapidly as a function of shear rate. The gradual transition from no-slip to steady-state slip flow is associated with faster relaxation of the polymer chains near the wall evaluated from decay of the time autocorrelation function of the first normal mode. We also show that at high melt densities the friction coefficient at the interface between the polymer melt and the solid wall follows a power-law decay as a function of the slip velocity. At large slip velocities the friction coefficient is determined by the product of the surface-induced peak in the structure factor, the temperature, and the contact density of the first fluid layer near the solid wall.

1 aPriezjev, N., V uhttps://icer.msu.edu/research/publications/shear-rate-threshold-boundary-slip-dense-polymer-films02667nas a2200157 4500008004100000245008500041210006900126260001200195300001400207490000800221520211000229100001902339700001302358700001802371856012002389 2009 eng d00aThermochemical Kinetics for Multi-reference Systems: Addition Reactions of Ozone0 aThermochemical Kinetics for Multireference Systems Addition Reac c04/2009 a5786-57990 v1133 aThe 1,3-dipolar cycloadditions of ozone to ethyne and ethene provide extreme examples of multireference singlet-state chemistry, and they are examined here to test the applicability of several approaches to thermochemical kinetics of systems with large static correlation. Four different multireference diagnostics are applied to measure the multireference characters of the reactants, products, and transition states; all diagnostics indicate significant multireference character in the reactant portion of the potential energy surfaces. We make a more complete estimation of the effect of quadruple excitations than was previously available, and we use this with CCSDT/CBS estimation of Wheeler et al. (Wheeler, S. E.; Ess, D. H.; Houk, K. N. J. Phys. Chem. A 2008, 112, 1798.) to make new best estimates of the van der Waals association energy, the barrier height, and the reaction energy to form the cycloadduct for both reactions. Comparing with these best estimates, we present comprehensive mean unsigned errors for a variety of coupled cluster, multilevel, and density functional methods. Several computational aspects of multireference reactions are considered: (i) the applicability of multilevel theory, (ii) the convergence of coupled cluster theory for reaction barrier heights, (iii) the applicability of completely renormalized coupled cluster methods to multireference systems, (iv) the treatment by density functional theory, (v) the multireference perturbation theory for multireference reactions, and (vi) the relative accuracy of scaling-type multilevel methods as compared with additive ones. It is found that scaling-type multilevel methods do not perform better than the additive-type multilevel methods. Among the 48 tested density functionals, only M05 reproduces the best estimates within their uncertainty. Multireference perturbation theory based on the complete-active-space reference wave functions constructed using a small number of reaction-specific active orbitals gives accurate forward barrier heights; however, it significantly underestimates reaction energies.

1 aPiecuch, Piotr1 aZhao, Y.1 aTruhlar, D.G. uhttps://icer.msu.edu/research/publications/thermochemical-kinetics-multi-reference-systems-addition-reactions-ozone02100nas a2200181 4500008004100000245008800041210006900129300001000198490000800208520148500216100001401701700001601715700001501731700001401746700001901760700001801779856012101797 2008 eng d00aApplication of Renormalized Coupled- Cluster Methods to Potential Function of Water0 aApplication of Renormalized Coupled Cluster Methods to Potential a59-780 v1203 aThe goal of this paper is to examine the performance of the conventional and renormalized single-reference coupled-cluster (CC) methods in calculations of the potential energy surface of the water molecule. A comparison with the results of the internally contracted multi-reference configuration interaction calculations including the quasi-degenerate Davidson correction (MRCI(Q)) and the spectroscopically accurate potential energy surface of water resulting from the use of the energy switching (ES) approach indicates that the relatively inexpensive completely renormalized (CR) CC methods with singles (S), doubles (D), and a non-iterative treatment of triples (T) or triples and quadruples (TQ), such as CR-CCSD(T), CR-CCSD(TQ), and the recently developed rigorously size extensive extension of CR-CCSD(T), termed CR-CC(2,3), provide substantial improvements in the results of conventional CCSD(T) and CCSD(TQ) calculations at larger internuclear separations. It is shown that the CR-CC(2,3) results corrected for the effect of quadruply excited clusters through the CR-CC(2,3)+Q approach can compete with the highly accurate MRCI(Q) data. The excellent agreement between the CR-CC(2,3)+Q and MRCI(Q) results suggests ways of improving the global potential energy surface of water resulting from the use of the ES approach in the regions of intermediate bond stretches and intermediate energies connecting the region of the global minimum with the asymptotic regions.

1 aZheng, J.1 aGour, J., R1 aLutz, J.J.1 aWloch, M.1 aPiecuch, Piotr1 aTruhlar, D.G. uhttps://icer.msu.edu/research/publications/application-renormalized-coupled-cluster-methods-potential-function-water02156nas a2200181 4500008004100000245022700041210006900268260001200337490000800349520139600357100001401753700001601767700001501783700001401798700001901812700001801831856012501849 2008 eng d00aA Comparative Assessment of the Perturbative and Renormalized Coupled Cluster Theories with a Non-iterative Treatment of Triple Excitations for Thermochemical Kinetics, Including a Study of Basis Set and Core Correlation E0 aComparative Assessment of the Perturbative and Renormalized Coup c01/20080 v1283 aThe CCSD, CCSD(T), and CR-CC(2,3) coupled cluster methods, combined with five triple-zeta basis sets, namely, MG3S, aug-cc-pVTZ, aug-cc-pV(T+d)Z, aug-cc-pCVTZ, and aug-cc-pCV(T+d)Z, are tested against the DBH24 database of diverse reaction barrier heights. The calculations confirm that the inclusion of connected triple excitations is essential to achieving high accuracy for thermochemical kinetics. They show that various noniterative ways of incorporating connected triple excitations in coupled cluster theory, including the CCSD(T) approach, the full CR-CC(2,3) method, and approximate variants of CR-CC(2,3) similar to the triples corrections of the CCSD(2) approaches, are all about equally accurate for describing the effects of connected triply excited clusters in studies of activation barriers. The effect of freezing core electrons on the results of the CCSD, CCSD(T), and CR-CC(2,3) calculations for barrier heights is also examined. It is demonstrated that to include core correlation most reliably, a basis set including functions that correlate the core and that can treat core-valence correlation is required. On the other hand, the frozen-core approximation using valence-optimized basis sets that lead to relatively small computational costs of CCSD(T) and CR-CC(2,3) calculations can achieve almost as high accuracy as the analogous fully correlated calculations.

1 aZheng, J.1 aGour, J., R1 aLutz, J.J.1 aWloch, M.1 aPiecuch, Piotr1 aTruhlar, D.G. uhttps://icer.msu.edu/research/publications/comparative-assessment-perturbative-renormalized-coupled-cluster-theories-non00489nas a2200133 4500008004100000245006800041210006700109260001300176300001400189100001400203700001400217700001800231856010600249 2008 eng d00aHow a generative encoding fares as problem-regularity decreases0 aHow a generative encoding fares as problemregularity decreases bSpringer a358–3671 aClune, J.1 aOfria, C.1 aPennock, R.T. uhttps://icer.msu.edu/research/publications/how-generative-encoding-fares-problem-regularity-decreases01785nas a2200217 4500008004100000245008800041210006900129260001200198490000800210520105900218653001701277653003001294653001801324653001301342653001501355653001401370653002201384100001801406700002001424856012301444 2008 eng d00aRheological study of polymer flow past rough surfaces with slip boundary conditions0 aRheological study of polymer flow past rough surfaces with slip c10/20080 v1293 aThe slip phenomena in thin polymer films confined by either flat or periodically corrugated surfaces are investigated by molecular dynamics and continuum simulations. For atomically flat surfaces and weak wall-fluid interactions, the shear rate dependence of the slip length has a distinct local minimum which is followed by a rapid increase at higher shear rates. For corrugated surfaces with wavelength larger than the radius of gyration of polymer chains, the effective slip length decays monotonically with increasing corrugation amplitude. At small amplitudes, this decay is reproduced accurately by the numerical solution of the Stokes equation with constant and rate-dependent local slip length. When the corrugation wavelength is comparable to the radius of gyration, the continuum predictions overestimate the effective slip length obtained from molecular dynamics simulations. The analysis of the conformational properties indicates that polymer chains tend to stretch in the direction of shear flow above the crests of the wavy surface.

10aliquid films10amolecular dynamics method10apolymer melts10arheology10ashear flow10aslip flow10asurface roughness1 aNiavarani, A.1 aPriezjev, N., V uhttps://icer.msu.edu/research/publications/rheological-study-polymer-flow-past-rough-surfaces-slip-boundary-conditions01604nas a2200193 4500008004100000245009100041210006900132260001200201490000700213520093400220653002301154653001501177653001601192653001801208653002801226100001801254700002001272856011801292 2008 eng d00aSlip boundary conditions for shear flow of polymer melts past atomically flat surfaces0 aSlip boundary conditions for shear flow of polymer melts past at c04/20080 v773 aMolecular dynamics simulations are carried out to investigate the dynamic behavior of the slip length in thin polymer films confined between atomically smooth thermal surfaces. For weak wall-fluid interactions, the shear rate dependence of the slip length acquires a distinct local minimum followed by a rapid growth at higher shear rates. With increasing fluid density, the position of the local minimum is shifted to lower shear rates. We found that the ratio of the shear viscosity to the slip length, which defines the friction coefficient at the liquid/solid interface, undergoes a transition from a nearly constant value to power law decay as a function of the slip velocity. In a wide range of shear rates and fluid densities, the friction coefficient is determined by the product of the value of the surface-induced peak in the structure factor and the contact density of the first fluid layer near the solid wall.

10amolecular dynamics10ashear rate10aslip length10aslip velocity10asmooth thermal surfaces1 aNiavarani, A.1 aPriezjev, N., V uhttps://icer.msu.edu/research/publications/slip-boundary-conditions-shear-flow-polymer-melts-past-atomically-flat02436nas a2200205 4500008004100000245012200041210006900163260001200232300001400244490000800258520172300266100001701989700001602006700001402022700001402036700001902050700001802069700001802087856012502105 2008 eng d00aStereoelectronic Effects on Molecular Geometries and State-Energy Splittings of Ligated Monocopper Diozygen Complexes0 aStereoelectronic Effects on Molecular Geometries and StateEnergy c03/2008 a3754-37670 v1123 aThe relative energies of side-on versus end-on binding of molecular oxygen to a supported Cu(I) species, and the singlet versus triplet nature of the ground electronic state, are sensitive to the nature of the supporting ligands and, in particular, depend upon their geometric arrangement relative to the O2 binding site. Highly correlated ab initio and density functional theory electronic structure calculations demonstrate that optimal overlap (and oxidative charge transfer) occurs for the side-on geometry, and this is promoted by ligands that raise the energy, thereby enhancing resonance, of the filled Cu dxz orbital that hybridizes with the in-plane π* orbital of O2. Conversely, ligands that raise the energy of the filled Cu dz2 orbital foster a preference for end-on binding as this is the only mode that permits good overlap with the in-plane O2 π*. Because the overlap of Cu dz2 with O2 π* is reduced as compared to the overlap of Cu dxz with the same O2 orbital, the resonance is also reduced, leading to generally more stable triplet states relative to singlets in the end-on geometry as compared to the side-on geometry, where singlet ground states become more easily accessible once ligands are stronger donors. Biradical Cu(II)-O2 superoxide character in the electronic structure of the supported complexes leads to significant challenges for accurate quantum chemical calculations that are best addressed by exploiting the spin-purified M06L local density functional, single-reference completely renormalized coupled-cluster theory, or multireference second-order perturbation theory, all of which provide predictions that are qualitatively and quantitatively consistent with one another.

1 aCramer, C.J.1 aGour, J., R1 aKinal, A.1 aWloch, M.1 aPiecuch, Piotr1 aShahi, A.R.M.1 aGagliardi, L. uhttps://icer.msu.edu/research/publications/stereoelectronic-effects-molecular-geometries-state-energy-splittings-ligated02707nas a2200301 4500008004100000245017900041210006900220260001200289300001300301490000800314520164400322653003101966653003301997653002402030653001902054653001802073653001802091653001502109653002202124653002102146653003002167100001602197700001902213700001602232700001402248700001802262856012502280 2007 eng d00aActive-Space Symmetry-Adapted-Cluster Configuration-Interaction and Equation-of-Motion Cluster Methods for High Accuracy Calculations of Potential Energy Surfaces of Radicals0 aActiveSpace SymmetryAdaptedCluster ConfigurationInteraction and c04/2007 a28 pages0 v1263 aThe electron-attached (EA) and ionized (IP) symmetry-adapted-cluster configuration-interaction (SAC-CI) methods and their equation-of-motion coupled-cluster (EOMCC) analogs provide an elegant framework for studying open-shell systems. As shown in this study, these schemes require the presence of higher-order excitations, such as the four-particle-three-hole (4p-3h) or four-hole–three-particle (4h-3p) terms, in the electron attaching or ionizing operator R in order to produce accurate ground- and excited-state potential energy surfaces of radicals along bond breaking coordinates. The full inclusion of the 4p-3h/4h-3p excitations in the EA/IP SAC-CI and EOMCC methods leads to schemes which are far too expensive for calculations involving larger radicals and realistic basis sets. In order to reduce the large costs of such schemes without sacrificing accuracy, the active-space EA/IP EOMCC methodology [ J. R. Gour et al., J. Chem. Phys. 123, 134113 (2005) ] is extended to the EA/IP SAC-CI approaches with 4p-3h/4h-3p excitations. The resulting methods, which use a physically motivated set of active orbitals to pick out the most important 3p-2h/3h-2p and 4p-3h/4h-3p excitations, represent practical computational approaches for high-accuracy calculations of potential energy surfaces of radicals. To illustrate the potential offered by the active-space EA/IP SAC-CI approaches with up to 4p-3h/4h-3p excitations, the results of benchmark calculations for the potential energy surfaces of the low-lying doublet states of CH and OH are presented and compared with other SAC-CI and EOMCC methods, and full CI results.

10aconfiguration interactions10acoupled cluster calculations10aelectron attachment10aexcited states10afree radicals10aground states10aionisation10aorganic compounds10aoxygen compounds10apotential energy surfaces1 aOhtsuka, Y.1 aPiecuch, Piotr1 aGour, J., R1 aEhara, M.1 aNakatsuji, H. uhttps://icer.msu.edu/active-space-symmetry-adapted-cluster-configuration-interaction-and-equation-motion-cluster-methods01936nas a2200157 4500008004100000245009100041210006900132260001200201300001200213490000800225520137300233100001101606700001701617700001901634856012501653 2007 eng d00aBreaking Bonds with the Left Eigenstate Completely Renormalized Coupled-Cluster Method0 aBreaking Bonds with the Left Eigenstate Completely Renormalized c11/2007 a6 pages0 v1273 aThe recently developed [ P. Piecuch and M. Wloch, J. Chem. Phys. 123, 224105 (2005) ] size-extensive left eigenstate completely renormalized (CR) coupled-cluster (CC) singles (S), doubles (D), and noniterative triples (T) approach, termed CR-CC(2,3) and abbreviated in this paper as CCL, is compared with the full configuration interaction (FCI) method for all possible types of single bond-breaking reactions between C, H, Si, and Cl (except H2) and the H2SiSiH2 double bond-breaking reaction. The CCL method is in excellent agreement with FCI in the entire region R = 1–3Re for all of the studied single bond-breaking reactions, where R and Re are the bond distance and the equilibrium bond length, respectively. The CCL method recovers the FCI results to within approximately 1 mhartree in the region R = 1–3Re of the H–SiH3, H–Cl, H3Si–SiH3, Cl–CH3, H–CH3, and H3C–SiH3 bonds. The maximum errors are −2.1, 1.6, and 1.6 mhartree in the R = 1–3Re region of the H3C–CH3, Cl–Cl, and H3Si–Cl bonds, respectively, while the discrepancy for the H2SiSiH2 double bond-breaking reaction is 6.6 (8.5) mhartree at R = 2(3)Re. CCL also predicts more accurate relative energies than the conventional CCSD and CCSD(T) approaches, and the predecessor of CR-CC(2,3) termed CR-CCSD(T).

1 aGe, Y.1 aGordon, M.S.1 aPiecuch, Piotr uhttps://icer.msu.edu/research/publications/breaking-bonds-left-eigenstate-completely-renormalized-coupled-cluster-method03686nas a2200145 4500008004100000245018100041210006900222260001200291300001200303490000800315520305800323100001403381700001903395856012603414 2007 eng d00aComputational Investigation of the Conrotatory and Disrotatory Isomerization Channels of Bicyclo[1.1.0]butane to Buta-1,3-diene: A Completely Renormalized Coupled-Cluster Study0 aComputational Investigation of the Conrotatory and Disrotatory I c01/2007 a734-7420 v1113 aThe conrotatory and disrotatory mechanisms of the isomerization of bicyclo[1.1.0]butane to trans-buta-1,3-diene have been computationally investigated with the CASSCF, MCQDPT2, (U)B3LYP, CCSD(T), CR-CCSD(T), and CR-CC(2,3) approaches. The coupled-cluster (CC) methods, including the CC approach with singles, doubles, and noniterative triples (CCSD(T)), and its completely renormalized (CR) extensions called CR-CCSD(T) and CR-CC(2,3), and the density functional theory B3LYP approach do an excellent job of correctly predicting the activation barrier for the conrotatory pathway, which corresponds to a weakly biradical transition state (TS), producing values within experimental error bars. In particular, the recently developed CR-CC(2,3) method gives 40.8 or 41.1 kcal/mol, in perfect agreement with the experimental value of 40.6 ± 2.5 kcal/mol. The complete-active-space self-consistent-field (CASSCF) approach and the second-order multireference perturbation theory (MCQDPT2) are less accurate in describing the conrotatory barrier than CR-CC(2,3). The higher energy disrotatory pathway, which has not been characterized experimentally and which involves a strongly biradical TS, poses a great challenge for many methods. CCSD(T) fails, predicting the activation barrier for the disrotatory pathway significantly below the conrotatory barrier, contradicting the experimental result that the conrotatory pathway describes the mechanism. The strongly biradical character of the disrotatory TS, spin contamination, and the proximity of singlet and triplet potential energy surfaces cause difficulties for B3LYP, which does not link this TS with gauche-buta-1,3-diene. No such difficulties occur in the CASSCF calculations, which offer a proper description of the structure of the disrotatory TS that links it with the reactant and product molecules. The CR-CC(2,3) approach, which accurately balances dynamical and nondynamical correlations in systems containing closed-shell and biradical structures, predicts the activation enthalpy for the disrotatory mechanism of 66 kcal/mol. CR-CCSD(T) gives 69 kcal/mol. In agreement with experiment and earlier multireference configuration interaction calculations of Nguyen and Gordon, CR-CCSD(T) and CR-CC(2,3) favor the conrotatory mechanism. The CASSCF, MCQDPT2, and B3LYP methods correctly place the disrotatory barrier above the conrotatory one, but, on the basis of a comparison with the accurate CR-CC(2,3) results, they underestimate the activation energy for the disrotatory pathway. All CC approaches employed in this study produce very good estimates of the enthalpy of isomerization of bicyclo[1.1.0]butane into buta-1,3-diene, the experimental value of which is −25.9 ± 0.4 kcal/mol, giving about −28 kcal/mol, when trans-buta-1,3-diene is used as a product, and −25 kcal/mol, when the nearly isoenergetic gauche-buta-1,3-diene rotamer is used as a product. The CC reaction enthalpies are more accurate than those obtained with CASSCF, MCQDPT2, and B3LYP.

1 aKinal, A.1 aPiecuch, Piotr uhttps://icer.msu.edu/computational-investigation-conrotatory-and-disrotatory-isomerization-channels-bicyclo110butane-buta01210nas a2200193 4500008004100000245008000041210006900121260001200190300001200202490000700214520059600221100001400817700001600831700001400847700002100861700001800882700001900900856009700919 2007 eng d00aCoupled-Cluster and Configuration-Interaction Calculations for Heavy Nuclei0 aCoupledCluster and ConfigurationInteraction Calculations for Hea c03/2007 a4 pages0 v983 aWe compare coupled-cluster (CC) and configuration-interaction (CI) results for 56Ni obtained in the pf-shell basis, focusing on practical CC approximations that can be applied to systems with dozens or hundreds of correlated fermions. The weight of the reference state and the strength of correlation effects are controlled by the gap between the f7/2 orbit and the f5/2, p3/2, p1/2 orbits. Independent of the gap, the CC method with 1p-1h and 2p-2h clusters and a noniterative treatment of 3p-3h clusters is as accurate as the more demanding CI approach truncated at the 4p-4h level.

1 aHoroi, M.1 aGour, J., R1 aWloch, M.1 aLodriguito, M.D.1 aBrown, B., A.1 aPiecuch, Piotr uhttps://icer.msu.edu/coupled-cluster-and-configuration-interaction-calculations-heavy-nuclei01203nas a2200205 4500008004100000245005500041210005300096260001200149300001300161490000700174520063000181100001400811700001900825700001700844700001600861700001500877700001400892700001900906856007200925 2007 eng d00aCoupled-Cluster Theory for Three-Body Hamiltonians0 aCoupledCluster Theory for ThreeBody Hamiltonians c09/2007 a11 pages0 v763 aWe derive coupled-cluster equations for three-body Hamiltonians. The equations for the one- and two-body cluster amplitudes are presented in a factorized form that leads to an efficient numerical implementation. We employ low-momentum two- and three-nucleon interactions and calculate the binding energy of 4He. The results show that the main contribution of the three-nucleon interaction stems from its density-dependent zero-, one-, and two-body terms that result from the normal ordering of the Hamiltonian in coupled-cluster theory. The residual three-body terms that remain after normal ordering can be neglected.

1 aHagen, G.1 aPapenbrock, T.1 aDean, D., J.1 aSchwenk, A.1 aNHogga, A.1 aWloch, M.1 aPiecuch, Piotr uhttps://icer.msu.edu/coupled-cluster-theory-three-body-hamiltonians01385nas a2200217 4500008004100000245007200041210006900113260001200182300001100194490000800205520071100213653002200924653002400946653001700970653003000987653000901017653002201026653001501048100002001063856008401083 2007 eng d00aEffect of surface roughness on rate-dependent slip in simple fluids0 aEffect of surface roughness on ratedependent slip in simple flui c10/2007 a1447080 v1273 aMolecular dynamics simulations are used to investigate the influence of molecular-scale surface roughness on the slip behavior in thin liquid films. The slip length increases almost linearly with the shear rate for atomically smooth rigid walls and incommensurate structures of the liquid/solid interface. The thermal fluctuations of the wall atoms lead to an effective surface roughness, which makes the slip length weakly dependent on the shear rate. With increasing the elastic stiffness of the wall, the surface roughness smoothes out and the strong rate dependence is restored again. Both periodically and randomly corrugated rigid surfaces reduce the slip length and its shear rate dependence.

10aelastic constants10ainterface roughness10aliquid films10amolecular dynamics method10aslip10asurface roughness10athin films1 aPriezjev, N., V uhttps://icer.msu.edu/effect-surface-roughness-rate-dependent-slip-simple-fluids01855nas a2200157 4500008004100000245017000041210006900211260001200280300001600292490000800308520120900316100001401525700001601539700001901555856012301574 2007 eng d00aExtension of the Renormalized Coupled-Cluster Methods Exploiting Left Eigenstates of the Similarity-Transformed Hamiltonian to Open- Shell Systems: A Benchmark Study0 aExtension of the Renormalized CoupledCluster Methods Exploiting c11/2007 a11359-113820 v1113 aThe recently formulated completely renormalized coupled-cluster method with singles, doubles, and noniterative triples, exploiting the biorthogonal form of the method of moments of coupled-cluster equations (Piecuch, P.; Włoch, M. J. Chem. Phys. 2005, 123, 224105; Piecuch, P.; Włoch, M.; Gour, J. R.; Kinal, A. Chem. Phys. Lett. 2006, 418, 467), termed CR-CC(2,3), is extended to open-shell systems. Test calculations for bond breaking in the OH radical and the ion and singlet−triplet gaps in the CH2, HHeH, and (HFH)- biradical systems indicate that the CR-CC(2,3) approach employing the restricted open-shell Hartree−Fock (ROHF) reference is significantly more accurate than the widely used CCSD(T) method and other noniterative triples coupled-cluster approximations without making the calculations substantially more expensive. A few molecular examples, including the activation energies of the C2H4 + H → C2H5 forward and reverse reactions and the triplet states of the CH2 and H2Si2O2 biradicals, are used to show that the dependence of the ROHF-based CR-CC(2,3) energies on the method of canonicalization of the ROHF orbitals is, for all practical purposes, negligible.

1 aWloch, M.1 aGour, J., R1 aPiecuch, Piotr uhttps://icer.msu.edu/extension-renormalized-coupled-cluster-methods-exploiting-left-eigenstates-similarity-transformed01291nas a2200169 4500008004100000020002600041245012100067210006900188260004600257490000800303520060900311100001900920700002400939700001500963700001700978856012600995 2007 eng d aISBN13: 978084123843500aNew Alternatives for Accurate Electronic Structure Calculations of Potential Energy Surfaces Involving Bond Breaking0 aNew Alternatives for Accurate Electronic Structure Calculations aWashington, DCbAmerican Chemical Sociegy0 v9583 aThe method of moments of coupled-cluster equations (MMCC) is extended to potential energy surfaces involving multiple bond breaking by developing the quasi-variational (QV) and quadratic (Q) variants of the MMCC theory. The QVMMCC and QMMCC methods are related to the extended CC (ECC) theory, in which products involving cluster operators and their deexcitation counterparts mimic the effects of higher-order clusters. The test calculations for N2 show that the QMMCC and ECC methods can provide spectacular improvements in the description of multiple bond breaking by the standard CC approaches.

1 aPiecuch, Piotr1 aPimienta, I., S. O.1 aFan, P.-D.1 aKowalski, K. uhttps://icer.msu.edu/new-alternatives-accurate-electronic-structure-calculations-potential-energy-surfaces-involving-bond01199nas a2200133 4500008004100000245006200041210006100103260001200164300001000176490000700186520077300193100002000966856007900986 2007 eng d00aRate-dependent slip boundary conditions for simple fluids0 aRatedependent slip boundary conditions for simple fluids c05/2007 a516050 v753 aThe dynamic behavior of the slip length in a fluid flow confined between atomically smooth surfaces is investigated using molecular dynamics simulations. At weak wall-fluid interactions, the slip length increases nonlinearly with the shear rate provided that the liquid/solid interface forms incommensurable structures. A gradual transition to the linear rate dependence is observed upon increasing the wall-fluid interaction. We found that the slip length can be well described by a function of a single variable that in turn depends on the in-plane structure factor, contact density, and temperature of the first fluid layer near the solid wall. Extensive simulations show that this formula is valid in a wide range of shear rates and wall-fluid interactions.

1 aPriezjev, N., V uhttps://icer.msu.edu/rate-dependent-slip-boundary-conditions-simple-fluids03587nas a2200145 4500008004100000245011300041210006900154300001100223490000700234520302500241100001903266700001403285700002103299856012103320 2007 eng d00aRenormalized Coupled-Cluster Methods: Theoretical Foundations and Application to Potential Function of Water0 aRenormalized CoupledCluster Methods Theoretical Foundations and a63-1210 v163 aConventional single-reference methods fail when bond breaking and other situations characterized by larger non-dynamical correlation effects are examined. In consequence, the adequate treatment of molecular potential energy surfaces involving signiﬁcant bond rearrangements has been the domain of expert multi-reference methods. The question arises if one can develop practical single-reference procedures that could be applied to at least some of the most frequent multi-reference situations, such as single and double bond dissociations. This question is addressed in the present paper by examining the performance of the conventional and renormalized coupled-cluster (CC) methods in calculations of the potential enery surface of the water molecule. A comparison with the results of the highly accurate internally contracted multi-reference conﬁguration interaction calculations including the quasi-degenerate Davidson correction (MRCI(Q)) and the spectroscopically accurate potential energy surface of water resulting from the use of the energy switching (ES) approach indicates that the relatively inexpensive completely renormalized (CR) CC methods with singles (S), doubles (D), and a non-iterative treatment of triples (T) or triples and quadruples (TQ), such as CR-CCSD(T), CR-CCSD(TQ), and the recently developed rigorously size extensive extension of the CR-CCSD(T), termed CR-CC(2,3), provide considerable improvements in the results of conventional CCSD(T) and CCSD(TQ) calculations at larger internuclear separations. It is shown that the CR-CC(2,3) results a posteriori corrected for the effect of quadruply excited clusters (the CR-CC(2,3)+Q approach) can compete with the highly accurate MRCI(Q) data. The excellent agreement between the CR-CC(2,3)+Q and MRCI(Q) results suggests ways of improving the global potential energy surface of water resulting from the use of the ES approach in the regions of intermediate bond stretches and intermediate and higher energies connecting the region of the global minimum with the asymptotic regions. In addition to the examination of the performance of the CR-CCSD(T), CR-CCSD(TQ), CR-CC(2,3), and CR-CC(2,3)+Q approaches, we provide a thorough review of the method of moments of CC equations (MMCC), as applied to ground electronic states, including the most recent biorthogonal formulation of MMCC theory employing the left eigenstates of the similarity-transformed Hamiltonian, and other mathematical and physical concepts that lie behind all renormalized CC approximations. In particular, we discuss the similarities and differences between the older CR-CCSD(T) and CR-CCSD(TQ) approximations and the recently formulated size extensive renormalized CC methods, such as CR-CC(2,3), and open questions that emerge in the process of designing higher-order schemes based on the biorthogonalMMCC formalism, such as CR-CC(2,4), which describe the combined effect of triples (already present in CR-CC(2,3) calculations) and quadruples in a proper manner.

1 aPiecuch, Piotr1 aWloch, M.1 aVerandas, A.J.C. uhttps://icer.msu.edu/renormalized-coupled-cluster-methods-theoretical-foundations-and-application-potential-function01279nas a2200457 4500008004100000245014900041210006900190260001200259490000700271100001700278700001500295700001600310700001500326700001700341700001600358700001400374700001400388700001800402700001600420700001300436700001600449700001900465700001500484700001700499700001400516700001400530700001400544700001500558700001600573700001700589700001700606700001700623700001500640700001700655700001400672700001400686700001300700700001800713700001900731856007100750 2007 eng d00aShape and Structure of N = Z 64Ge: Electromagnetic Transition Rates from the Application ￼of the Recoil Distance Method to a Knockout Reaction0 aShape and Structure of N Z 64Ge Electromagnetic Transition Rates c07/20070 v991 aStarosta, K.1 aDewald, A.1 aDunomes, A.1 aAdrich, P.1 aAmthor, A.M.1 aBaumann, T.1 aBazin, D.1 aBowen, M.1 aBrown, B., A.1 aChester, A.1 aGade, A.1 aGalaviz, D.1 aGlasmacher, T.1 aGinter, T.1 aHausmann, M.1 aHoroi, M.1 aJolie, J.1 aMelon, B.1 aMiller, D.1 aMoeller, V.1 aNorris, R.P.1 aPissulla, T.1 aPortillo, M.1 aRother, W.1 aShimbara, Y.1 aStolz, A.1 aVaman, C.1 aVoss, P.1 aWeisshaar, D.1 aZelevinsky, V. uhttp://journals.aps.org/prl/abstract/10.1103/PhysRevLett.99.04250301273nas a2200205 4500008004100000245008900041210006900130260001200199300001200211490000700223520060600230100001900836700001400855700001700869700001600886700002600902700001900928700001700947856010300964 2006 eng d00aAb Initio Coupled-Cluster Calculations for Nuclei Using Methods of Quantum Chemistry0 aAb Initio CoupledCluster Calculations for Nuclei Using Methods o c09/2005 a485-4880 v253 aWe report preliminary large scale ab initio calculations of ground and excited states of 16O using quantum chemistry inspired coupled cluster methods and realistic two-body interactions. By using the renormalized Hamiltonians obtained with a no-core G-matrix approach, we obtain the virtually converged results at the level of two-body interactions. Due to the polynomial scaling with the system size that characterizes coupled cluster methods, we can probe large model spaces with up to seven major oscillator shells, for which standard non-truncated shell-model calculations are not possible.

1 aPiecuch, Piotr1 aWloch, M.1 aDean, D., J.1 aGour, J., R1 aHjorth-Jensen}, M., {1 aPapenbrock, T.1 aKowalski, K. uhttps://icer.msu.edu/ab-initio-coupled-cluster-calculations-nuclei-using-methods-quantum-chemistry01862nas a2200181 4500008004100000245005700041210005600098260001200154300001400166490000800180520132100188100001501509700001901524700002001543700001801563700002401581856007501605 2006 eng d00aAb initio determination of solid-state nanostructure0 aAb initio determination of solidstate nanostructure c07/2005 a655–6580 v4403 aAdvances in materials science and molecular biology followed rapidly from the ability to characterize atomic structure using single crystals1, 2, 3, 4. Structure determination is more difficult if single crystals are not available5. Many complex inorganic materials that are of interest in nanotechnology have no periodic long-range order and so their structures cannot be solved using crystallographic methods6. Here we demonstrate that ab initio structure solution of these nanostructured materials is feasible using diffraction data in combination with distance geometry methods. Precise, sub-ångström resolution distance data are experimentally available from the atomic pair distribution function (PDF)6, 7. Current PDF analysis consists of structure refinement from reasonable initial structure guesses6, 7 and it is not clear, a priori, that sufficient information exists in the PDF to obtain a unique structural solution. Here we present and validate two algorithms for structure reconstruction from precise unassigned interatomic distances for a range of clusters. We then apply the algorithms to find a unique, ab initio, structural solution for C60 from PDF data alone. This opens the door to sub-ångström resolution structure solution of nanomaterials, even when crystallographic methods fail.

1 aJuhás, P.1 aCherba, D., M.1 aDuxbury, P., M.1 aPunch, W., F.1 aBillinge, S., J. L. uhttps://icer.msu.edu/ab-initio-determination-solid-state-nanostructure01498nas a2200181 4500008004100000245011900041210006900160260001200229300001200241490000800253520084400261100001901105700001501124700001701139700001501156700002401171856012101195 2006 eng d00aAutomated derivation and parallel computer implementation of renormalized and active-space coupled-cluster methods0 aAutomated derivation and parallel computer implementation of ren c08/2005 a79–970 v1063 aOur recent efforts that have led to an automated derivation and computer implementation of the renormalized and active-space coupled-cluster {(CC)} methods with Tensor Contraction Engine {(TCE)} are summarized. The {TCE-generated} renormalized and active-space {CC} computer codes are parallel and applicable to closed- and open-shell references, enabling accurate calculations of potential energy surfaces along bond-breaking coordinates and excited states displaying a significant multi-reference character. The effectiveness of the new codes in describing electronic quasi-degeneracies is illustrated by the renormalized {CC} calculations of the potential energy curve of {HCl} and the active-space {CC} calculations for the low-lying excited states of the Be3 system. © 2005 Wiley Periodicals, Inc. Int J Quantum Chem, 2006

1 aPiecuch, Piotr1 aHirata, So1 aKowalski, K.1 aFan, P.-D.1 aWindus, Theresa, L. uhttps://icer.msu.edu/automated-derivation-and-parallel-computer-implementation-renormalized-and-active-space-coupled00864nas a2200193 4500008004100000245003800041210003800079300001400117490000700131520031100138653006000449100001900509700001700528700001600545700001400561700002600575700001400601856005500615 2006 eng d00aCoupled Cluster Theory for Nuclei0 aCoupled Cluster Theory for Nuclei a5338-53450 v203 aThis presentation focuses on some of the recent developments in low-energy nuclear structure theory, with emphasis on applications of coupled-cluster theory. We report on results for ground and excited states in 4He and 16O, and about extensions of coupled-cluster theory to treat three-body forces.

10aNuclear structure; light nuclei; coupled-cluster theory1 aPapenbrock, T.1 aDean, D., J.1 aGour, J., R1 aHagen, G.1 aHjorth-Jensen}, M., {1 aWloch, M. uhttps://icer.msu.edu/coupled-cluster-theory-nuclei01833nas a2200181 4500008004100000245006500041210006400106260001100170300001300181490000700194520127600201100001901477700001601496700002601512700001401538700001701552856008201569 2006 eng d00aCoupled-Cluster Calculations for Valence Systems around 16 O0 aCoupledCluster Calculations for Valence Systems around 16 O c8/2006 a18 pages0 v743 aWe study the ground and low-lying excited states of 15O, 17O, 15N, and 17F using modern two-body nucleon-nucleon interactions and the suitably designed variants of the ab initio equation-of-motion coupled-cluster theory aimed at an accurate description of systems with valence particles and holes. A number of properties of 15O, 17O, 15N, and 17F, including ways the energies of ground and excited states of valence systems around 16O change as functions of the number of nucleons, are correctly reproduced by the equation-of-motion coupled-cluster calculations performed in up to eight major-oscillator shells. Certain disagreements with experiment are in part because of the degrees of freedom such as three-body interactions not accounted for in our effective two-body Hamiltonians. In particular, the calculated binding energies of 15O/15N and 17O/17F enable us to rationalize the discrepancy between the experimental and recently published [Phys. Rev. Lett. 94, 212501 (2005)] equation-of-motion coupled-cluster excitation energies for the Jπ=3- state of 16O. Our calculations demonstrate the feasibility of the equation-of-motion coupled-cluster methods to deal with valence systems around closed-shell nuclei and to provide results for systems beyond A=16.

1 aPiecuch, Piotr1 aGour, J., R1 aHjorth-Jensen}, M., {1 aWloch, M.1 aDean, D., J. uhttps://icer.msu.edu/coupled-cluster-calculations-valence-systems-around-16-o01855nas a2200181 4500008004100000245006400041210006300105260001200168300001100180490000700191520130200198100001601500700001901516700002601535700001401561700001701575856008101592 2006 eng d00aCoupled-cluster calculations for valence systems around O160 aCoupledcluster calculations for valence systems around O16 c08/2006 a0243100 v743 aWe study the ground and low-lying excited states of {15O,} {17O,} {15N,} and {17F} using modern two-body nucleon-nucleon interactions and the suitably designed variants of the ab initio equation-of-motion coupled-cluster theory aimed at an accurate description of systems with valence particles and holes. A number of properties of {15O,} {17O,} {15N,} and {17F,} including ways the energies of ground and excited states of valence systems around {16O} change as functions of the number of nucleons, are correctly reproduced by the equation-of-motion coupled-cluster calculations performed in up to eight major-oscillator shells. Certain disagreements with experiment are in part because of the degrees of freedom such as three-body interactions not accounted for in our effective two-body Hamiltonians. In particular, the calculated binding energies of {15O/15N} and {17O/17F} enable us to rationalize the discrepancy between the experimental and recently published {[Phys.} Rev. Lett. 94, 212501 (2005)] equation-of-motion coupled-cluster excitation energies for the Jπ=3- state of {16O.} Our calculations demonstrate the feasibility of the equation-of-motion coupled-cluster methods to deal with valence systems around closed-shell nuclei and to provide results for systems beyond A=16.

1 aGour, J., R1 aPiecuch, Piotr1 aHjorth-Jensen}, M., {1 aWloch, M.1 aDean, D., J. uhttps://icer.msu.edu/coupled-cluster-calculations-valence-systems-around-o1601911nas a2200193 4500008004100000245014700041210006900188260001200257300001300269490000800282520117900290653003301469653001801502653002201520653002201542100001601564700001901580856011801599 2006 eng d00aEfficient Formulation and Computer Implementation of the Active-Space Electron-Attached and Ionized Equation-of-Motion Coupled-Cluster Methods0 aEfficient Formulation and Computer Implementation of the ActiveS c12/2006 a17 pages0 v1253 aThe efficient, general-purpose implementations of the active-space electron-attached (EA) and ionized (IP) equation-of-motion coupled-cluster (EOMCC) methods including up to 3p-2h and 3h-2p excitations, called EA-EOMCCSDt and IP-EOMCCSDt, respectively, are discussed. The details of the algorithm that enables one to achieve a high degree of code vectorization for the active-space methods and the factorized forms of the EA- and IP-EOMCCSDt equations that maximize the benefits of using active orbitals in the process of selecting the dominant 3p-2h and 3h-2p excitations are presented. The results of benchmark calculations for the low-lying doublet and quartet states of the CH and SH radicals reveal that the active-space EA-EOMCCSDt and IP-EOMCCSDt methods are capable of producing results for the electronic excitations in open-shell systems that match the high accuracy of EA- and IP-EOMCC calculations with a full treatment of 3p-2h and 3h-2p excitations, even when the excited states of interest display a manifestly multideterminantal nature, with the costs that can be on the same order of those characterizing the basic EOMCC singles and doubles approach.

10acoupled cluster calculations10afree radicals10aorganic compounds10asulphur compounds1 aGour, J., R1 aPiecuch, Piotr uhttps://icer.msu.edu/efficient-formulation-and-computer-implementation-active-space-electron-attached-and-ionized02232nas a2200253 4500008004100000245008800041210006900129260001100198300001400209490000800223520146400231100001901695700001601714700001401730700001701744700001501761700001801776700001401794700001701808700001401825700001801839700001501857856010601872 2006 eng d00aExperimental and Theoretical UV Characterizations of Acetyloacetone and its Isomers0 aExperimental and Theoretical UV Characterizations of Acetyloacet c2/2006 a3920-39260 v1103 aCryogenic matrix isolation experiments have allowed the measurement of the UV absorption spectra of the high-energy non-chelated isomers of acetylacetone, these isomers being produced by UV irradiation of the stable chelated form. Their identification has been done by coupling selective UV-induced isomerization, infrared spectroscopy, and harmonic vibrational frequency calculations using density functional theory. The relative energies of the chelated and non-chelated forms of acetylacetone in the S0 state have been obtained using density functional theory and coupled-cluster methods. For each isomer of acetylacetone, we have calculated the UV transition energies and dipole oscillator strengths using the excited-state coupled-cluster methods, including EOMCCSD (equation-of-motion coupled-cluster method with singles and doubles) and CR-EOMCCSD(T) (the completely renormalized EOMCC approach with singles, doubles, and non-iterative triples). For dipole-allowed transition energies, there is a very good agreement between experiment and theory. In particular, the CR-EOMCCSD(T) approach explains the blue shift in the electronic spectrum due to the formation of the non-chelated species after the UV irradiation of the chelated form of acetylacetone. Both experiment and CR-EOMCCSD(T) theory identify two among the seven non-chelated forms to be characterized by red-shifted UV transitions relative to the remaining five non-chelated isomers.

1 aPiecuch, Piotr1 aCoussan, S.1 aFerro, Y.1 aTrivella, A.1 aRoubin, P.1 aWieczorek, R.1 aManca, C.1 aKowalski, K.1 aWloch, M.1 aKucharski, S.1 aMusial, M. uhttps://icer.msu.edu/experimental-and-theoretical-uv-characterizations-acetyloacetone-and-its-isomers01765nas a2200169 4500008004100000245014000041210006900181260001100250300001400261490000800275520098500283653015801268100001901426700001601445700001401461856012001475 2006 eng d00aExtension of the Active-Space Equation-of- Motion Coupled-Cluster Methods to Radical Systems: The EA-EOMCCSDt and IPEOMCCSDt Approaches0 aExtension of the ActiveSpace Equationof Motion CoupledCluster Me c7/2006 a2854-28740 v1063 aThe development of the active-space variants of the electron-attached (EA) and ionized (IP) equation-of-motion coupled-cluster (EOMCC) methods, in which higher-than-doubly excited components of the cluster operator T and higher than 2p-1h or 2h-1p components of the electron attaching and ionizing operators R are defined through the use of active orbitals, is discussed. As shown by preliminary test calculations of adiabatic excitation energies and potential energy curves for the low-lying states of the CH and OH radicals, the basic active-space EA-EOMCC and IP-EOMCC methods, referred to as the EA-EOMCCSDt and IP-EOMCCSDt approaches, are capable of accuratelydescribing the ground and excited states of open-shell systems, even at the moderately stretched nuclear geometries and even for states with a strong multi-determinantal or doubly excited character, at the low costs that are on the order of those characterizing the standard EOMCC singles and doubles method.

10aoupled-cluster theory;equation-of-a motion coupled-cluster method;active-space coupled-cluster approaches;electronic-attached and ionized states;radicals1 aPiecuch, Piotr1 aGour, J., R1 aWloch, M. uhttps://icer.msu.edu/extension-active-space-equation-motion-coupled-cluster-methods-radical-systems-ea-eomccsdt-and00839nas a2200145 4500008004100000245009700041210006900138260001500207300001200222490000800234520030100242100002100543700001900564856011000583 2006 eng d00aExtrapolating Potential Energy Surfaces by Scaling Electron Correlation at a Single Geometry0 aExtrapolating Potential Energy Surfaces by Scaling Electron Corr c10/30/2006 a448-4530 v4303 aIt is shown that the molecular potential energy surface corresponding to a high level of ab initio theory can be accurately predicted by performing calculations with smaller basis sets and then scaling the electron correlation at a single point calculated with the larger target basis set.

1 aVarandas, A.J.C.1 aPiecuch, Piotr uhttps://icer.msu.edu/extrapolating-potential-energy-surfaces-scaling-electron-correlation-single-geometry01358nas a2200301 4500008004100000245003200041210003100073260001200104300001100116490000700127520059800134100002000732700002000752700001800772700002200790700001900812700001400831700002400845700001900869700002000888700001400908700001500922700001400937700001800951700001900969700001800988856005001006 2006 eng d00aHalf-life and spin of 60Mng0 aHalflife and spin of 60Mng c04/2006 a0443220 v733 aA value of 0.28±0.02 s has been deduced for the half-life of the ground state of {60Mn,} in sharp contrast to the previously adopted value of 51±6 s. Access to the low-spin {60Mn} ground state was accomplished via β decay of the 0+ {60Cr} parent nuclide. New low-energy states in {60Mn} have been identified from β-delayed γ-ray spectroscopy. The new, shorter half-life of {60Mng} is not suggestive of isospin-forbidden β decay, and new spin and parity assignments of 1+ and 4+ have been adopted for the ground and isomeric β-decaying states, respectively, of {60Mn.}

1 aLiddick, S., N.1 aMantica, P., F.1 aBrown, B., A.1 aCarpenter, M., P.1 aDavies, A., D.1 aHoroi, M.1 aJanssens, R., V. F.1 aMorton, A., C.1 aMueller, W., F.1 aPavan, J.1 aSchatz, H.1 aStolz, A.1 aTabor, S., L.1 aTomlin, B., E.1 aWiedeking, M. uhttps://icer.msu.edu/half-life-and-spin-60mng00743nas a2200277 4500008004100000245003200041210003100073260001200104490000700116100002000123700002000143700001800163700002200181700001900203700001400222700002400236700001900260700002000279700001400299700001500313700001400328700001800342700001900360700001800379856006800397 2006 eng d00aHalf-life and spin of 60Mng0 aHalflife and spin of 60Mng c04/20060 v731 aLiddick, S., N.1 aMantica, P., F.1 aBrown, B., A.1 aCarpenter, M., P.1 aDavies, A., D.1 aHoroi, M.1 aJanssens, R., V. F.1 aMorton, A., C.1 aMueller, W., F.1 aPavan, J.1 aSchatz, H.1 aStolz, A.1 aTabor, S., L.1 aTomlin, B., E.1 aWiedeking, M. uhttp://journals.aps.org/prc/abstract/10.1103/PhysRevC.73.04432202648nas a2200157 4500008004100000245016100041210006900202260001500271300000900286490000800295520182400303653020902127100001502336700001602351856012302367 2006 eng d00aIntriguing Accuracies of the Exponential Wave Function Expansions Exploiting Finite Two-Body Correlation Operators in Calculations for Many-Electron Systems0 aIntriguing Accuracies of the Exponential Wave Function Expansion c08/31/2006 a3-160 v7683 aFollowing the ideas laid down by Nooijen and Nakatsuji, several authors have considered an intriguing possibility of representing the exact many-electron wave functions by the exponential cluster expansions involving two-body correlation operators. In particular, inspired by the symmetric form of the Horn–Weinstein exact energy formula, and exploiting the variational principle and numerical analysis, we have demonstrated that one can obtain nearly exact ground-state wave functions for a few many-electron systems using the exponential cluster expansion involving a finite two-body operator acting on the Hartree–Fock determinant [P. Piecuch et al., Phys. Rev. Lett. 90 (2003) 113001]. After summarizing these earlier findings and making some additional comments on the nature of the exponential cluster expansions involving two-body correlation operators, we examine the following issues: (i) the improvements in the accuracy and convergence toward the full configuration interaction (CI) limit offered by cluster operators containing two-body as well as one-body components, (ii) the improvements in the accuracy resulting from the use of multi-determinantal reference states, and (iii) the potential accuracy of the exponential wave function expansions involving finite one- and two-body cluster operators in excited-state calculations. All calculations are performed for an eight electron model system, which is simple enough to allow for the exact, full CI, and other electronic structure calculations, which has fewer independent parameters in the Hamiltonian than the dimension of the corresponding full CI problem, and which enables one to examine ground and excited states with a varying degree of configurational quasi-degeneracy by simple changes in the corresponding nuclear geometry.

10axact many-electron wave functions; Generalized coupled-cluster methods; Two-body correlation operators; Nooijen's conjecture; Variational calculations; Multi-determinantal reference states; Excited states1 aFan, P.-D.1 aPiecuch, P. uhttps://icer.msu.edu/intriguing-accuracies-exponential-wave-function-expansions-exploiting-finite-two-body-correlation01624nas a2200145 4500008004100000245014800041210006900189260001100258300001200269490000800281520103500289100001901324700001401343856012101357 2006 eng d00aIs the Mechanism of the [2+2] Cycloaddition of Cyclopentyne to Ethylene Concerted or Biradical? A Completely Renormalized Coupled Cluster Study0 aMechanism of the 22 Cycloaddition of Cyclopentyne to Ethylene Co c6/2005 a367-3780 v1103 aThe mechanism of the [2+2] cycloaddition reaction of cyclopentyne to ethylene has been studied using the completely renormalized coupled cluster method with singles, doubles, and noniterative triples (CR−CCSD(T)). In agreement with the experimentally observed stereochemistry, the CR−CCSD(T) method favors the concerted pathway involving a [2+1] transition state, whereas the popular CCSD(T) method, which is often regarded as the “gold standard” of electronic structure theory, and low-order multireference methods support the less probable biradical mechanism. In addition, the CCSD(T) approach produces an erroneous description of some transition states and intermediates, particularly those which have a significant biradical character. The CR−CCSD(T) calculations indicate that the reaction is a highly exothermic (Δ = −68 kcal/mol), predominantly concerted process with a relatively low activation barrier on the order of 13−16 kcal/mol which permits its thermal occurrence.

1 aPiecuch, Piotr1 aKinal, A. uhttps://icer.msu.edu/mechanism-22-cycloaddition-cyclopentyne-ethylene-concerted-or-biradical-completely-renormalized01919nas a2200181 4500008004100000245010400041210006900145260001200214300001100226490000800237520110200245653019501347100001901542700002101561700001701582700001401599856012401613 2006 eng d00aNon-Iterative Coupled- Cluster Methods Employing Multi-Reference Perturbation Theory Wave Functions0 aNonIterative Coupled Cluster Methods Employing MultiReference Pe c10/2006 a89-1040 v7713 aA new class of non-iterative coupled-cluster (CC) methods, which improve the results of standard CC and equation-of-motion (EOM) CC calculations for ground and excited-state potential energy surfaces along bond breaking coordinates and for excited states dominated by two-electron transitions, is explored. The proposed approaches combine the method of moments of coupled-cluster equations (MMCC), in which the a posteriori corrections due to higher-order correlations are added to standard CC/EOMCC energies, with the multi-reference many-body perturbation theory (MRMBPT), which provides information about the most essential non-dynamic and dynamic correlation effects that are relevant to electronic quasi-degeneracies. The performance of the basic MRMBPT-corrected MMCC approximation, in which inexpensive non-iterative corrections due to triple excitations are added to ground- and excited-state energies obtained with the CC/EOMCC singles and doubles approach, is illustrated by the results of a few test calculations, including bond breaking in HF and H2O, and excited states of CH+.

10aCoupled-cluster theory; Equation-of-motion coupled-cluster methods; Method of moments of coupled-cluster equations; Multi-reference perturbation theory; Non-iterative coupled-cluster methods1 aPiecuch, Piotr1 aLodriguito, M.D.1 aKowalski, K.1 aWloch, M. uhttps://icer.msu.edu/non-iterative-coupled-cluster-methods-employing-multi-reference-perturbation-theory-wave-functions00503nas a2200145 4500008004100000245007200041210006900113300001100182490000700193100001900200700001400219700001900233700001600252856008900268 2006 eng d00aNon-iterative Coupled-Cluster Methods for Excited Electronic States0 aNoniterative CoupledCluster Methods for Excited Electronic State a45-1060 v151 aPiecuch, Piotr1 aWloch, M.1 aLodriguito, M.1 aGour, J., R uhttps://icer.msu.edu/non-iterative-coupled-cluster-methods-excited-electronic-states01338nas a2200169 4500008004100000245011100041210006900152260001200221300001400233490000800247520073400255100001900989700001401008700001601022700001401038856011601052 2006 eng d00aSingle-reference, size-extensive, non-iterative coupled-cluster approaches to bond breaking and biradicals0 aSinglereference sizeextensive noniterative coupledcluster approa c02/2006 a467–4740 v4183 aWe propose the non-iterative, completely renormalized (CR) coupled-cluster (CC) approaches, including the CR-CC(2, 3) method which offers considerable improvements over the CCSD(T) approach without a significant increase in the computer effort. The CR-CC(2, 3) method, in which the CCSD (CC singles and doubles) energy is corrected for the effect of triples, is size extensive, competitive with CCSD(T) in calculations for non-degenerate states, and as accurate as the expensive CC approach with singles, doubles, and triples in the bond-breaking region. Calculations of the activation enthalpy for the thermal isomerizations of cyclopropane involving trimethylene suggest that CR-CC(2, 3) may be applicable to biradicals.

1 aPiecuch, Piotr1 aWloch, M.1 aGour, J., R1 aKinal, A. uhttps://icer.msu.edu/single-reference-size-extensive-non-iterative-coupled-cluster-approaches-bond-breaking-and01465nas a2200181 4500008004100000245010100041210006900142260001500211300001600226490000800242520084100250100001701091700001401108700001401122700001901136700001801155856011001173 2006 eng d00aTheoretical Characterization of End-on and Side-on Peroxide Coordination in Ligated Cu2O2 Models0 aTheoretical Characterization of Endon and Sideon Peroxide Coordi c09/15/2006 a11557-115680 v1103 aThe relative energetics of μ-η1:η1 (trans end-on) and μ-η2:η2 (side-on) peroxo isomers of Cu2O2 fragments supported by 0, 2, 4, and 6 ammonia ligands have been computed with various density functional, coupled-cluster, and multiconfigurational protocols. There is substantial disagreement between the different levels for most cases, although completely renormalized coupled-cluster methods appear to offer the most reliable predictions. The significant biradical character of the end-on peroxo isomer proves problematic for the density functionals, while the demands on active space size and the need to account for interactions between different states in second-order perturbation theory prove challenging for the multireference treatments. In the latter case, it proved impossible to achieve any convincing convergence.

1 aCramer, C.J.1 aKinal, A.1 aWloch, M.1 aPiecuch, Piotr1 aGagliardi, L. uhttps://icer.msu.edu/theoretical-characterization-end-and-side-peroxide-coordination-ligated-cu2o2-models02131nas a2200181 4500008004100000245012100041210006900162260001200231300001600243490000800259520146800267100001701735700001401752700001901766700002401785700001801809856012201827 2006 eng d00aTheoretical Models on the Cu2O2 Torture Track. Mechanistic Implications for Oxytyrosinase and Small-molecule Analogs0 aTheoretical Models on the Cu2O2 Torture Track Mechanistic Implic c06/2007 a1991–20040 v1103 aAccurately describing the relative energetics of alternative bis(mu-oxo) and mu-eta2:eta2 peroxo isomers of Cu2O2 cores supported by 0, 2, 4, and 6 ammonia ligands is remarkably challenging for a wide variety of theoretical models, primarily owing to the difficulty of maintaining a balanced description of rapidly changing dynamical and nondynamical electron correlation effects and a varying degree of biradical character along the isomerization coordinate. The completely renormalized coupled-cluster level of theory including triple excitations and extremely efficient pure density functional levels of theory quantitatively agree with one another and also agree qualitatively with experimental results for Cu2O2 cores supported by analogous but larger ligands. Standard coupled-cluster methods, such as CCSD(T), are in most cases considerably less accurate and exhibit poor convergence in predicted relative energies. Hybrid density functionals significantly underestimate the stability of the bis(mu-oxo) form, with the magnitude of the error being directly proportional to the percentage Hartree-Fock exchange in the functional. Single-root CASPT2 multireference second-order perturbation theory, by contrast, significantly overestimates the stability of bis(mu-oxo) isomers. Implications of these results for modeling the mechanism of C-H bond activation by supported Cu2O2 cores, like that found in the active site of oxytyrosinase, are discussed.

1 aCramer, C.J.1 aWloch, M.1 aPiecuch, Piotr1 aPuzzarini, Cristina1 aGagliardi, L. uhttps://icer.msu.edu/theoretical-models-cu2o2-torture-track-mechanistic-implications-oxytyrosinase-and-small-molecule00614nas a2200157 4500008004100000245012500041210006900166260001100235300001400246490000800260100001900268700001400287700002100301700001600322856011800338 2006 eng d00aTwo New Classes of Non-Iterative Coupled-Cluster Methods Derived from the Method of Moments of Coupled-Cluster Equations0 aTwo New Classes of NonIterative CoupledCluster Methods Derived f c7/2006 a2149-21720 v1041 aPiecuch, Piotr1 aWloch, M.1 aLogriguito, M.D.1 aGour, J., R uhttps://icer.msu.edu/two-new-classes-non-iterative-coupled-cluster-methods-derived-method-moments-coupled-cluster02773nas a2200145 4500008004100000245019000041210006900231260001200300300000900312490000700321520214700328100001502475700001902490856011802509 2006 eng d00aThe Usefulness of Exponential Wave Function Expansions Employing One- and Two-Body Cluster Operators in Electronic Structure Theory: The Extended and Generalized Coupled-Cluster Methods0 aUsefulness of Exponential Wave Function Expansions Employing One c12/2006 a1-570 v513 aIn this paper, the applicability of exponential cluster expansions involving one- and two-body operators in high accuracy ab initio electronic structure calculations is examined. First, the extended coupled-cluster method with singles and doubles (ECCSD) is tested in the demanding studies of systems with strong quasi-degeneracies, including potential energy surfaces involving multiple bond breaking. The numerical results show that the single-reference ECCSD method is capable of providing a qualitatively correct description of quasi-degenerate electronic states and potential energy surfaces involving bond breaking, eliminating, in particular, the failures and the unphysical behavior of standard coupled-cluster methods in similar cases. It is also demonstrated that one can obtain entire potential energy surfaces with millihartree accuracies by combining the ECCSD theory with the non-iterative a posteriori corrections obtained by using the generalized variant of the method of moments of coupled-cluster equations. This is one of the first instances where the relatively simple single-reference formalism, employing only one- and two-body clusters in the design of the relevant energy expressions, provides a highly accurate description of the dynamic and significant non-dynamic correlation effects characterizing quasi-degenerate and multiply bonded systems. Second, an evidence is presented that one may be able to represent the virtually exact ground- and excited-state wave functions of many-electron systems by exponential cluster expansions employing general two-body or one- and two-body operators. Calculations for small many-electron model systems indicate the existence of finite two-body parameters that produce the numerically exact wave functions for ground and excited states. This finding may have a significant impact on future quantum calculations for many-electron systems, since normally one needs triply excited, quadruply excited, and other higher-than-doubly excited Slater determinants, in addition to all singly and doubly excited determinants, to obtain the exact or virtually exact wave functions.

1 aFan, P.-D.1 aPiecuch, Piotr uhttps://icer.msu.edu/usefulness-exponential-wave-function-expansions-employing-one-and-two-body-cluster-operators01260nas a2200205 4500008004100000245004300041210004200084260001200126300001100138490000700149520068900156100001500845700001700860700001600877700002600893700001700919700001900936700001600955856008300971 2005 eng d00aAb Initio Coupled-Cluster Study of 16O0 aAb Initio CoupledCluster Study of 16O c06/2005 a2125010 v943 aWe report converged results for the ground and excited states and matter density of 16O using realistic two-body nucleon-nucleon interactions and coupled-cluster methods and algorithms developed in quantum chemistry. Most of the binding is obtained with the coupled-cluster singles and doubles approach. Additional binding due to three-body clusters (triples) is minimal. The coupled-cluster method with singles and doubles provides a good description of the matter density, charge radius, charge form factor, and excited states of a one-particle, one-hole nature, but it cannot describe the first-excited 0+ state. Incorporation of triples has no effect on the latter finding.

1 aWłoch, M.1 aDean, D., J.1 aGour, J., R1 aHjorth-Jensen}, M., {1 aKowalski, K.1 aPapenbrock, T.1 aPiecuch, P. uhttps://icer.msu.edu/research/publications/ab-initio-coupled-cluster-study-16o01233nas a2200193 4500008004100000245004100041210004000082260001200122490000700134520068900141100001900830700001400849700001700863700001600880700002600896700001700922700001900939856008100958 2005 eng d00aAb Initio Coupled-Cluster Study of O0 aAb Initio CoupledCluster Study of O c06/20050 v943 aWe report converged results for the ground and excited states and matter density of 16O using realistic two-body nucleon-nucleon interactions and coupled-cluster methods and algorithms developed in quantum chemistry. Most of the binding is obtained with the coupled-cluster singles and doubles approach. Additional binding due to three-body clusters (triples) is minimal. The coupled-cluster method with singles and doubles provides a good description of the matter density, charge radius, charge form factor, and excited states of a one-particle, one-hole nature, but it cannot describe the first-excited 0+ state. Incorporation of triples has no effect on the latter finding.

1 aPiecuch, Piotr1 aWloch, M.1 aDean, D., J.1 aGour, J., R1 aHjorth-Jensen}, M., {1 aKowalski, K.1 aPapenbrock, T. uhttps://icer.msu.edu/research/publications/ab-initio-coupled-cluster-study-o01316nas a2200181 4500008004100000245006800041210006600109260001200175300001200187490000800199520074000207100001900947700001700966700001500983700001400998700001701012856010501029 2005 eng d00aActive-Space Coupled-Cluster Study of Electronic States of Be 30 aActiveSpace CoupledCluster Study of Electronic States of Be 3 c08/2005 a6 pages0 v1233 aThe active-space coupled-cluster (CC) and equation-of-motion (EOM) CC methods with all single and double excitations with triple excitations defined via active orbitals (CCSDt, EOMCCSDt), as implemented with TENSOR CONTRACTION ENGINE, are applied to the challenging Be3 system, which is characterized by a large number of low-lying excited states dominated by two-electron transitions and significant high-order correlation effects in the ground electronic state. It is demonstrated that the CCSDt and EOMCCSDt methods provide an excellent description of complicated electronic quasidegeneracies present in the Be3 cluster. Different strategies for defining triple excitations within the CCSDt∕EOMCCSDt approach are discussed.

1 aPiecuch, Piotr1 aKowalski, K.1 aHirata, S.1 aWloch, M.1 aWindus, T.L. uhttps://icer.msu.edu/research/publications/active-space-coupled-cluster-study-electronic-states-be-301392nas a2200181 4500008004100000245015300041210006900194300001600263490000800279520065800287653003300945653001800978653003200996100002201028700001901050700001701069856012401086 2005 eng d00aActive-space equation-of-motion coupled-cluster methods for excited states of radicals and other open-shell systems: {EA-EOMCCSDt} and {IP-EOMCCSDt}0 aActivespace equationofmotion coupledcluster methods for excited a134113–140 v1233 aThe previously developed active-space coupled-cluster (CC) and equation-of-motion (EOM) CC methods are extended to radicals and other open-shell systems by combining them with the electron attached (EA) and ionized (IP) EOMCC approaches. As illustrated by the calculations for the CH and OH radicals, the resulting EA-EOMCCSDt and IP-EOMCCSDt theories are capable of providing a highly accurate description of the electronic spectra of radical systems, including excited states displaying a manifestly multideterminantal nature, with the low costs that are not much greater that those characterizing the standard EOMCC singles and doubles method.

10acoupled cluster calculations10afree radicals10amolecular electronic states1 aGour, Jeffrey, R.1 aPiecuch, Piotr1 aWloch, Marta uhttps://icer.msu.edu/research/publications/active-space-equation-motion-coupled-cluster-methods-excited-states-radicals00613nas a2200145 4500008004100000245014900041210006900190260001200259300001300271490000800284100001900292700001600311700001400327856012600341 2005 eng d00aActive-Space Equation-of=Motion Coupled-Cluster Methods for Excited States of Radicals and Other Open-Shell Systems: EA-EOMCCSDt and IP-EOMCCSDt0 aActiveSpace EquationofMotion CoupledCluster Methods for Excited c10/2005 a14 pages0 v1231 aPiecuch, Piotr1 aGour, J., R1 aWloch, M. uhttps://icer.msu.edu/research/publications/active-space-equation-ofmotion-coupled-cluster-methods-excited-states-radicals01208nas a2200145 4500008004100000245017600041210006900217260001500286300001400301490000800315520057100323100001900894700002300913856012600936 2005 eng d00aBalancing Dynamic and Non-Dynamic Correlation for Diradical and Aromatic Transition States: A Renormalized Coupled-Cluster Study of the Cope Rearrangement of 1,5-Hexadiene0 aBalancing Dynamic and NonDynamic Correlation for Diradical and A c02/05/2005 a2608-26140 v1273 aSingle-reference coupled-cluster calculations employing the completely renormalized CCSD(T) (CR-CCSD(T)) approach have been used to examine the mechanism of the Cope rearrangement of 1,5-hexadiene. In agreement with multireference perturbation theory, the CR-CCSD(T) method favors the concerted mechanism of the Cope rearrangement involving an aromatic transition state. The CCSD(T) approach, which is often regarded as the “gold standard” of electronic structure theory, seems to fail in this case, favoring pathways through diradical structures.

1 aPiecuch, Piotr1 aMcGuire}, M., J. { uhttps://icer.msu.edu/research/publications/balancing-dynamic-non-dynamic-correlation-diradical-aromatic-transition-states02028nas a2200193 4500008004100000245012400041210006900165260005600234300001000290490000800300520128900308100001901597700001401616700001601630700001701646700002601663700001901689856012601708 2005 eng d00aBridging Quantum Chemistry and Nuclear Structure Theory: Coupled-Cluster Calculations for Closed- and Open-Shell Nuclei0 aBridging Quantum Chemistry and Nuclear Structure Theory CoupledC aMelville, NYbAmerican Institute of Physicsc7/2005 a28-450 v7773 aWe review basic elements of the single-reference coupled-cluster theory and discuss large scale ab initio calculations of ground and excited states of 15O, 16O, and 17O using coupled-cluster methods and algorithms developed in quantum chemistry. By using realistic two-body interactions and the renormalized form of the Hamiltonian obtained with a no-core G-matrix approach, we obtain the converged results for 16O and promising preliminary results for 15O and 17O at the level of two-body interactions. The calculated properties other than energies include matter density, charge radius, and charge form factor. The relatively low costs of coupled-cluster calculations, which are characterized by the low-order polynomial scaling with the system size, enable us to probe large model spaces with up to 7 or 8 major oscillator shells, for which non-truncated shell-model calculations for nuclei with A = 15 17 active particles are presently not possible. We argue that the use of coupled-cluster methods and computer algorithms developed by quantum chemists to calculate properties of nuclei is an important step toward the development of accurate and affordable many-body theories that cross the boundaries of various physical sciences. ©2005 American Institute of Physics

1 aPiecuch, Piotr1 aWloch, M.1 aGour, J., R1 aDean, D., J.1 aHjorth-Jensen}, M., {1 aPapenbrock, T. uhttps://icer.msu.edu/bridging-quantum-chemistry-and-nuclear-structure-theory-coupled-cluster-calculations-closed-and-open01552nas a2200169 4500008004100000245026000041210006900301260001200370300001600382490000800398520078000406100001901186700001501205700001801220700002301238856012101261 2005 eng d00aCan a Single-Reference Approach Provide a Balanced Description of Ground and Excited States? A Comparison of the Completely Renormalized Equation-of-the-Motion Coupled-Cluster Method with Multi-Reference Quasi-Degenerate Perturbation Theory Near a Conical0 aCan a SingleReference Approach Provide a Balanced Description of c11/2005 a11643-116460 v1093 aWe calculated the two lowest electronically adiabatic potential energy surfaces of ammonia in the region of the conical intersection and at a sequence of geometries along which one of the N-H bonds is broken. We employed both a multireference (MR) method and a single-reference (SR) method. The MR calculations are based on multiconfiguration quasidegenerate perturbation theory (MC-QDPT) with a 6-311+G(3df,3pd) basis set. The SR calculations, carried out with the same basis, employ the completely renormalized equation-ofmotion coupled-cluster method with singles and doubles, and a noniterative treatment of triples, denoted CR-EOMCCSD(T). At 91 geometries used for comparison, including geometries near a conical intersection, the surfaces agree to 7% on average.

1 aPiecuch, Piotr1 aNangia, S.1 aTruhlar, D.G.1 aMcGuire}, M., J. { uhttps://icer.msu.edu/research/publications/can-single-reference-approach-provide-balanced-description-ground-excited01534nas a2200265 4500008004100000245007500041210006900116260001500185300001200200490000800212520073300220100001900953700002000972700001600992700001301008700001701021700001401038700002201052700001801074700001401092700001701106700001301123700001701136856011501153 2005 eng d00aComparison of Low-Order Multireference Many-Body Perturbation Theories0 aComparison of LowOrder Multireference ManyBody Perturbation Theo c04/01/2005 a9 pages0 v1223 aTests have been made to benchmark and assess the relative accuracies of low-order multireference perturbation theories as compared to coupled cluster (CC) and full configuration interaction (FCI) methods. Test calculations include the ground and some excited states of the Be, H(2), BeH(2), CH(2), and SiH(2) systems. Comparisons with FCI and CC calculations show that in most cases the effective valence shell Hamiltonian (H(v)) method is more accurate than other low-order multireference perturbation theories, although none of the perturbative methods is as accurate as the CC approximations. We also briefly discuss some of the basic differences among the multireference perturbation theories considered in this work.

1 aPiecuch, Piotr1 aChaudhuri, R.K.1 aFreed, K.F.1 aHose, G.1 aKowalski, K.1 aWloch, M.1 aChattopadhyay, S.1 aMukherjee, D.1 aRolik, R.1 aSzabados, A.1 aToth, G.1 aSurjan, P.R. uhttps://icer.msu.edu/research/publications/comparison-low-order-multireference-many-body-perturbation-theories01895nas a2200133 4500008004100000245012300041210006900164260001400233490000800247520134500255100001901600700001901619856012301638 2005 eng d00aA Comparison of Renormalized Coupled-Cluster and Multireference Methods with Full Configuration Interaction Benchmarks0 aComparison of Renormalized CoupledCluster and Multireference Met c3/22/20050 v1223 aUnusual bonding and electronic near degeneracies make the lowest-lying singlet states of the C2 molecule particularly challenging for electronic structure theory. Here we compare two alternative approaches to modeling bond-breaking reactions and excited states: sophisticated multireference configuration interaction and multireference perturbation theory methods, and a more "black box," single-reference approach, the completely renormalized coupled-cluster method. These approximate methods are assessed in light of their ability to reproduce the full configuration interaction potential energy curves for the X1Sigmag+, B1Deltag, and B' 1Sigmag+ states of C2, which are numerically exact solutions of the electronic Schrodinger equation within the space spanned by a 6-31G* basis set. Both the multireference methods and the completely renormalized coupled-cluster approach provide dramatic improvements over the standard single-reference methods. The multireference methods are nearly as reliable for this challenging test case as for simpler reactions which break only single bonds. The completely renormalized coupled-cluster approach has difficulty for large internuclear separations R in this case, but over the wide range of R=1.0-2.0 A, it compares favorably with the more complicated multireference methods.

1 aPiecuch, Piotr1 aSherrill, C.D. uhttps://icer.msu.edu/comparison-renormalized-coupled-cluster-and-multireference-methods-full-configuration-interaction00768nas a2200169 4500008004100000245007500041210006900116260002500185520018800210100001900398700001700417700002200434700001700456700001900473700001400492856009200506 2005 eng d00aCoupled Cluster Approaches to Nuclei, Ground States and Excited States0 aCoupled Cluster Approaches to Nuclei Ground States and Excited S aPaestum, Italyc20053 aWe present recent coupled-cluster studies of nuclei, with an emphasis on ground state and excited states of closed shell nuclei. Perspectives for future studies are delineated.

1 aPiecuch, Piotr1 aDean, D., J.1 aJhorth-Jensen, M.1 aKowalski, K.1 aPapenbrock, T.1 aWloch, M. uhttps://icer.msu.edu/coupled-cluster-approaches-nuclei-ground-states-and-excited-states01156nas a2200157 4500008004100000245012800041210006900169260001200238490000800250520055100258100001900809700001400828700001600842700001700858856012300875 2005 eng d00aExtension of Renormalized Coupled-Cluster Methods Including Triple Excitations to Electronic States of Open-Shell Molecules0 aExtension of Renormalized CoupledCluster Methods Including Tripl c06/20050 v1223 aThe general-purpose open-shell implementation of the completely renormalized equation-of-motion coupled-cluster approach with singles, doubles, and noniterative triples [CR-EOMCCSD(T)] is reported. Benchmark calculations for the low-lying doublet and quartet states of the CH radical show that the CR-EOMCCSD(T) method is capable of providing a highly accurate description of ground and excited states of open-shell molecules. This includes states with strong double excitation character, for which the conventional EOMCCSD approach fails.

1 aPiecuch, Piotr1 aWloch, M.1 aGour, J., R1 aKowalski, K. uhttps://icer.msu.edu/research/publications/extension-renormalized-coupled-cluster-methods-including-triple-excitations02334nas a2200133 4500008004100000245006900041210006800110260001500178490000800193520185400201100001902055700001702074856010902091 2005 eng d00aExtensive Generalization of Renormalized Coupled-Cluster Methods0 aExtensive Generalization of Renormalized CoupledCluster Methods c02/09/20050 v1223 aThe recently developed completely renormalized (CR) coupled-cluster (CC) methods with singles, doubles, and noniterative triples or triples and quadruples [CR-CCSD(T) or CR-CCSD(TQ), respectively], which are based on the method of moments of CC equations (MMCC) [K. Kowalski and P. Piecuch, J. Chem. Phys. 113, 18 (2000)], eliminate the failures of the standard CCSD(T) and CCSD(TQ) methods at larger internuclear separations, but they are not rigorously size extensive. Although the departure from strict size extensivity of the CR-CCSD(T) and CR-CCSD(TQ) methods is small, it is important to examine the possibility of formulating the improved CR-CC methods, which are as effective in breaking chemical bonds as the existing CR-CCSD(T) and CR-CCSD(TQ) approaches, which are as easy to use as the CR-CCSD(T) and CR-CCSD(TQ) methods, and which can be made rigorously size extensive. This may be particularly useful for the applications of CR-CC methods and other MMCC approaches in calculations of potential energy surfaces of large many-electron systems and van der Waals molecules, where the additive separability of energies in the noninteracting limit is very important. In this paper, we propose different types of CR-CC approximations, termed the locally renormalized (LR) CCSD(T) and CCSD(TQ) methods, which become rigorously size extensive if the orbitals are localized on nointeracting fragments. The LR-CCSD(T) and LR-CCSD(TQ) methods rely on the form of the energy expression in terms of the generalized moments of CC equations, derived in this work, termed the numerator-denominator-connected MMCC expansion. The size extensivity and excellent performance of the LR-CCSD(T) and LR-CCSD(TQ) methods are illustrated numerically by showing the results for the dimers of stretched HF and LiH molecules and bond breaking in HF and H2O.

1 aPiecuch, Piotr1 aKowalski, K. uhttps://icer.msu.edu/research/publications/extensive-generalization-renormalized-coupled-cluster-methods01726nas a2200157 4500008004100000245013900041210006900180260001200249300001400261490000800275520111600283100001901399700001701418700001701435856011601452 2005 eng d00aNoniterative Corrections to Extended Coupled-Cluster Energies Employing the Generalized Method of Moments of Coupled-Cluster Equations0 aNoniterative Corrections to Extended CoupledCluster Energies Emp c08/2005 a2191-22130 v1033 aIt is shown that the extended coupled-cluster method with singles and doubles (ECCSD) does not suffer from the non-variational collapse observed in the standard CCSD calculations when multiple bond breaking is examined. This interesting feature of the single-reference ECCSD theory is used to design the non-iterative CC methods with singles, doubles and non-iterative triples and quadruples, which provide a highly accurate and variational description of potential energy surfaces involving multiple bond breaking with computational steps that scale as with the system size. This is accomplished with the help of the generalized version of the method of moments of coupled-cluster equations (GMMCC), which can be used to correct the results of non-standard CC calculations, such as ECCSD. The theoretical considerations are illustrated by the preliminary results of the ECCSD-based GMMCC calculations for triple bond breaking in N2. Keywords: Coupled-cluster theory; Extended coupled-cluster method; Method of moments of coupled-cluster equations; Non-iterative coupled-cluster approaches; Bond breaking

1 aPiecuch, Piotr1 aFan, {P.-D.}1 aKowalski, K. uhttps://icer.msu.edu/research/publications/noniterative-corrections-extended-coupled-cluster-energies-employing01746nas a2200217 4500008004100000245008700041210006900128260001200197300001200209490000800221520103700229100001901266700001701285700001601302700001401318700002601332700001701358700001901375700001401394856012001408 2005 eng d00aNuclear Structure Calculations with Coupled-Cluster Methods from Quantum Chemistry0 aNuclear Structure Calculations with CoupledCluster Methods from c04/2005 a299-3080 v7523 aWe present several coupled-cluster calculations of ground and excited states of 4He and 16O employing methods from quantum chemistry. A comparison of coupled cluster results with the results of exact diagonalization of the hamiltonian in the same model space and other truncated shell-model calculations shows that the quantum chemistry inspired coupled cluster approximations provide an excellent description of ground and excited states of nuclei, with much less computational effort than traditional large-scale shell-model approaches. Unless truncations are made, for nuclei like 16O, full-fledged shell-model calculations with four or more major shells are not possible. However, these and even larger systems can be studied with the coupled cluster methods due to the polynomial rather than factorial scaling inherent in standard shell-model studies. This makes the coupled cluster approaches, developed in quantum chemistry, viable methods for describing weakly bound systems of interest for future nuclear facilities.

1 aPiecuch, Piotr1 aDean, D., J.1 aGour, J., R1 aHagen, G.1 aHjorth-Jensen}, M., {1 aKowalski, K.1 aPapenbrock, T.1 aWloch, M. uhttps://icer.msu.edu/research/publications/nuclear-structure-calculations-coupled-cluster-methods-quantum-chemistry02915nas a2200313 4500008004100000245011100041210006900152260001200221300001600233490000800249520189000257653002102147653003102168653003302199653001302232653001902245653001302264653001802277653002102295653002302316653001802339653002202357653002202379653002902401653001002430100001902440700001702459856012502476 2005 eng d00aRenormalized coupled-cluster methods exploiting left eigenstates of the similarity-transformed Hamiltonian0 aRenormalized coupledcluster methods exploiting left eigenstates c12/2005 a224105–100 v1233 aCompletely renormalized (CR) coupled-cluster (CC) approaches, such as CR-CCSD(T), in which one corrects the standard CC singles and doubles (CCSD) energy for the effects of triply (T) and other higher-than-doubly excited clusters [ K. Kowalski and P. Piecuch, J. Chem. Phys. 113, 18 (2000) ], are reformulated in terms of the left eigenstates 〈Φ∣L of the similarity-transformed Hamiltonian of CC theory. The resulting CR-CCSD(T)L or CR-CC(2,3) and other CR-CCL methods are derived from the new biorthogonal form of the method of moments of CC equations (MMCC) in which, in analogy to the original MMCC theory, one focuses on the noniterative corrections to standard CC energies that recover the exact, full configuration-interaction energies. One of the advantages of the biorthogonal MMCC theory, which will be further analyzed and extended to excited states in a separate paper, is a rigorous size extensivity of the basic ground-state CR-CCL approximations that result from it, which was slightly violated by the original CR-CCSD(T) and CR-CCSD(TQ) approaches. This includes the CR-CCSD(T)L or CR-CC(2,3) method discussed in this paper, in which one corrects the CCSD energy by the relatively inexpensive noniterative correction due to triples. Test calculations for bond breaking in HF, F2, and H2O indicate that the noniterative CR-CCSD(T)L or CR-CC(2,3) approximation is very competitive with the standard CCSD(T) theory for nondegenerate closed-shell states, while being practically as accurate as the full CC approach with singles, doubles, and triples in the bond-breaking region. Calculations of the activation enthalpy for the thermal isomerizations of cyclopropane involving the trimethylene biradical as a transition state show that the noniterative CR-CCSD(T)L approximation is capable of providing activation enthalpies which perfectly agree with experiment.

10abonds (chemical)10aconfiguration interactions10acoupled cluster calculations10aenthalpy10aexcited states10afluorine10aground states10aheat of reaction10ahydrogen compounds10aisomerisation10amethod of moments10aorganic compounds10areaction kinetics theory10awater1 aPiecuch, Piotr1 aWloch, Marta uhttps://icer.msu.edu/renormalized-coupled-cluster-methods-exploiting-left-eigenstates-similarity-transformed-hamiltonian01158nas a2200229 4500008004100000245007700041210006900118260001500187300001400202490000800216520046200224100001900686700001600705700001700721700001700738700001700755700001400772700001700786700002200803700001500825856008800840 2005 eng d00aWhere Does the Planar-to-Nonplanar Turnover Occur in Small Gold Clusters0 aWhere Does the PlanartoNonplanar Turnover Occur in Small Gold Cl c12/30/2004 a1049-10520 v1273 aSeveral levels of theory, including both Gaussian-based and plane wave density functional theory (DFT), second-order perturbation theory (MP2), and coupled cluster methods (CCSD(T)), are employed to study Au6 and Au8 clusters. All methods predict that the lowest energy isomer of Au6 is planar. For Au8, both DFT methods predict that the two lowest isomers are planar. In contrast, both MP2 and CCSD(T) predict the lowest Au8 isomers to be nonplanar.

1 aPiecuch, Piotr1 aOlson, R.M.1 aVarganov, S.1 aGordon, M.S.1 aChretien, S.1 aMetiu, H.1 aKowalski, K.1 aKucharski, S., A.1 aMusial, M. uhttps://icer.msu.edu/where-does-planar-nonplanar-turnover-occur-small-gold-clusters02386nas a2200241 4500008004100000245015000041210006900191260001200260300001400272490000800286520138300294653017701677100001901854700001701873700002401890700001501914700002101929700002301950700002201973700001301995700001502008856012102023 2004 eng d00aMethod of moments of coupled-cluster equations: a new formalism for designing accurate electronic structure methods for ground and excited states0 aMethod of moments of coupledcluster equations a new formalism fo c07/2004 a349–3930 v1123 aThe method of moments of coupled-cluster equations {(MMCC),} which provides a systematic way of improving the results of the standard coupled-cluster {(CC)} and equation-of-motion {CC} {(EOMCC)} calculations for the ground- and excited-state energies of atomic and molecular systems, is described. The {MMCC} theory and its generalized {MMCC} {(GMMCC)} extension that enables one to use the cluster operators resulting from the standard as well as nonstandard {CC} calculations, including those obtained with the extended {CC} {(ECC)} approaches, are based on rigorous mathematical relationships that define the many-body structure of the differences between the full configuration interaction {(CI)} and {CC} or {EOMCC} energies. These relationships can be used to design the noniterative corrections to the {CC/EOMCC} energies that work for chemical bond breaking and potential energy surfaces of excited electronic states, including excited states dominated by double excitations, where the standard single-reference {CC/EOMCC} methods fail. Several {MMCC} and {GMMCC} approximations are discussed, including the renormalized and completely renormalized {CC/EOMCC} methods for closed- and open-shell states, the quadratic {MMCC} approaches, the {CI-corrected} {MMCC} methods, and the {GMMCC} approaches for multiple bond breaking based on the {ECC} cluster amplitudes.

10aCoupled-cluster theory - Method of moments of coupled-cluster equations - Renormalized coupled-cluster methods - extended coupled cluster theory - Potential energy surfaces1 aPiecuch, Piotr1 aKowalski, K.1 aPimienta, I., S. O.1 aFan, P.-D.1 aLodriguito, M.D.1 aMcGuire}, M., J. {1 aKucharski, S., A.1 aKuś, T.1 aMusial, M. uhttps://icer.msu.edu/research/publications/method-moments-coupled-cluster-equations-new-formalism-designing-accurate