A High-Performance Fortran Code to Calculate Spin- and Parity-Dependent Nuclear Level Densities

TL;DR

This paper introduces a high-performance Fortran code that efficiently calculates spin- and parity-dependent nuclear level densities using an extended statistical spectroscopy method, applicable to large model spaces beyond direct diagonalization.

Contribution

The paper presents a novel Fortran implementation for exact calculation of nuclear level densities with spin and parity, extending statistical spectroscopy methods to larger model spaces.

Findings

Successfully applied to 28Si and 64Ge nuclei.

Estimated ground state energy of 64Ge in large model space.

Demonstrated efficiency over direct shell model diagonalization.

Abstract

A high-performance Fortran code is developed to calculate the spin- and parity-dependent shell model nuclear level densities.The algorithm is based on the extension of methods of statistical spectroscopy and implies exact calculation of the first and second Hamiltonian moments for different configurations at fixed spin and parity. The proton-neutron formalism is used. We have applied the method for calculating the level densities for a set of nuclei in the sd-, pf-, and pf+g9/2 - model spaces. Examples of the calculations for 28Si (in the sd-model space) and 64Ge (in the pf+g9/2-model space) are presented. To illustrate the power of the method we estimate the ground state energy of 64Ge in the larger model space pf+g9/2, which is not accessible to direct shell model diagonalization due to the prohibitively large dimension, by comparing with the nuclear level densities at low excitation energy calculated in the smaller model space pf.