From deformed Hartree-Fock to the nucleon-pair approximation

Abstract

The nucleon-pair approximation (NPA) can be a compact alternative to full configuration-interaction (FCI) diagonalization in nuclear shell-model spaces, but selecting good pairs is a long-standing problem. While seniority-based pairs work well for near-spherical 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 Hartree-Fock 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.

arXiv comment7 pages, 4 figures

References in corpus (10)

• The Shell Model as Unified View of Nuclear Structure
• Shell model study of the isobaric chains A=50, A=51 and A=52
• Factorization in large-scale many-body calculations
• A monopole-optimized effective interaction for tin isotopes
• BIGSTICK: A flexible configuration-interaction shell-model code (updated)
• RPA vs. exact shell-model correlation energies
• Measurable bounds for Entanglement of Formation
• Nucleons pair shell model in M-scheme
• Generalized seniority for the shell model with realistic interactions
• Practical Calculation Scheme for Generalized Seniority

Cited by in corpus (6)

• Recent progress in configuration-interaction shell model
• Nuclear states projected from a pair condensate
• The nucleon-pair approximation for nuclei from spherical to deformed regions
• Nucleon-pair coupling scheme in Elliott's SU(3) model
• Nucleon-pair truncation of the shell model for medium-heavy nuclei
• The pervasiveness of shape coexistence in nuclear pair condensates