Coupled-Cluster and Configuration-Interaction Calculations for Heavy Nuclei
|Title||Coupled-Cluster and Configuration-Interaction Calculations for Heavy Nuclei|
|Publication Type||Journal Article|
|Year of Publication||2007|
|Authors||Horoi, M, Gour, JR, Wloch, M, Lodriguito, MD, Brown, BA, Piecuch, P|
|Journal||Physical Review Lettters|
We 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.