Systematics of the first 2+ excitation in spherical nuclei with Skryme-QRPA

TL;DR

This study systematically evaluates the energies and transition strengths of the first 2+ excited states in spherical nuclei using Skyrme-QRPA, highlighting differences between SkM* and SLy4 functionals and comparing with GCM results.

Contribution

It provides a comprehensive analysis of 2+ excitation energies in spherical nuclei using QRPA with Skyrme interactions, comparing different functionals and with GCM methods.

Findings

SkM* functional yields excitation energies 11% higher than experimental values.

SkM* performs better than SLy4 in average and dispersion of energies.

QRPA reproduces trends near closed shells more accurately than GCM.

Abstract

We use the Quasiparticle Random Phase Approximation (QRPA) and the Skyrme interactions SLy4 and SkM* to systematically calculate energies and transition strengths for the lowest 2+ state in spherical even-even nuclei.The SkM* functional, applied to 178 spherical nuclei between Z=10 and 90, produces excitation energies that are on average 11% higher than experimental values, with residuals that fluctuate about the average by -35%+55%. The predictions of SkM* and SLy4 have significant differences, in part because of differences in the calculated ground state deformations; SkM* performs better in both the average and dispersion of energies. Comparing the QRPA results with those of generator-coordinate-method (GCM) calculations, we find that the QRPA reproduces trends near closed shells better than the GCM, and overpredicts the energies less severely in general. We attribute part of the difference to a deficiency in the way the GCM is implemented.