Excitation spectra from angular momentum projection of Hartree-Fock states and the configuration-interaction shell-model

TL;DR

This paper compares excitation spectra obtained from angular-momentum projection of Hartree-Fock states with those from configuration-interaction shell-model calculations across various nuclear shells, highlighting strengths and limitations.

Contribution

It provides a direct numerical comparison between two computational methods for nuclear spectra within the same model spaces and Hamiltonians.

Findings

Accurately reproduces spectra for rotational nuclei

Less accurate for vibrational and complex spectra

Highlights method strengths and limitations

Abstract

We make numerical comparison of spectra from angular-momentum projection on Hartree-Fock states with spectra from configuration-interaction nuclear shell-model calculations, all carried out in the same model spaces (in this case the sd, lower pf, and p-sd_5/2 shells) and using the same input Hamiltonians. We find, unsurprisingly, that the low-lying excitation spectra for rotational nuclides are well reproduced, but the spectra for vibrational nuclides, and more generally the complex specta for odd-A and odd-odd nuclides are less well reproduced in detail.