From deformed HartreeFock to the nucleonpair approximation
Abstract
The nucleonpair approximation (NPA) can be a compact alternative to full configurationinteraction (FCI) diagonalization in nuclear shellmodel spaces, but selecting good pairs is a longstanding problem. While senioritybased pairs work well for nearspherical nuclides, they do not work well for deformed nuclides with strong rotational bands. We propose an alternate approach. We show how one can write any Slater determinant for an even number of particles as a general pair condensate, from which one can project out pairs of good angular momentum. We implement this by generating unconstrained HartreeFock states in a shell model basis and extracting S, D, and G pairs. The subsequent NPA calculations yield good agreement with FCI results using the same effective interactions.
 Publication:

Physics Letters B
 Pub Date:
 October 2020
 DOI:
 10.1016/j.physletb.2020.135705
 arXiv:
 arXiv:1909.08785
 Bibcode:
 2020PhLB..80935705F
 Keywords:

 Nuclear Theory
 EPrint:
 7 pages, 4 figures