Finite-temperature mean-field approximations for shell model Hamiltonians: the code HF-SHELL

TL;DR

The paper introduces HF-SHELL, a versatile code for solving finite-temperature mean-field equations in shell model Hamiltonians, accommodating various approximations and deformations, with applications to nuclear state densities.

Contribution

HF-SHELL is a new computational tool that enables self-consistent mean-field calculations for shell model Hamiltonians, including particle-number projection and triaxial deformations.

Findings

Supports ground-state and finite-temperature calculations.

Incorporates particle-number projection for canonical ensemble.

Handles triaxial quadrupole deformations.

Abstract

We present the code HF-SHELL for solving the self-consistent mean-field equations for configuration-interaction shell model Hamiltonians in the proton-neutron formalism. The code can calculate both ground-state and finite-temperature properties in the Hartree-Fock (HF), HF+Bardeen-Cooper-Schrieffer (HF+BCS), and the Hartree-Fock-Bogoliubov (HFB) mean-field approximations. Particle-number projection after variation is incorporated to reduce the grand-canonical ensemble to the canonical ensemble, making the code particularly suitable for the calculation of nuclear state densities. The code does not impose axial symmetry and allows for triaxial quadrupole deformations. The self-consistency cycle is particularly robust through the use of the heavy-ball optimization technique and the implementation of different options to constrain the quadrupole degrees of freedom.