Isoscalar giant monopole resonance in Sn isotopes using a quantum molecular dynamics model

TL;DR

This study uses an isospin-dependent quantum molecular dynamics model to investigate the isoscalar giant monopole resonance in Sn isotopes, successfully reproducing experimental data by incorporating isospin and mass number dependencies.

Contribution

It introduces an improved IQMD model that accounts for isospin dependence and variable nucleon wave-packet widths to better match experimental GMR data in isotopes.

Findings

GMR peak energies are overestimated without isospin effects.

Including isospin dependence improves agreement with experimental data.

The model accurately reproduces GMR properties across multiple isotopes.

Abstract

The isoscalar giant monopole resonance (ISGMR) in Sn isotopes and other nuclei is investigated in the framework of the isospin-dependent quantum molecular dynamics (IQMD) model. The spectrum of GMR is calculated by taking the root-mean-square (RMS) radius of a nucleus as its monopole moment. The peak energy, the full width at half maximum (FWHM), and the strength of GMR extracted by a Gaussian fit to the spectrum have been studied. The GMR peak energies for Sn isotopes from the calculations using a mass-number dependent Gaussian wave-packet width $\sigma_r$ for nucleons are found to be overestimated and show a weak dependence on the mass number compared with the experimental data. However, it is found that experimental data of the GMR peak energies for $^{56}$Ni, $^{90}$Zr, and $^{208}$Pb as well as Sn isotopes can be nicely reproduced after taking into account the isospin dependence in isotope chains in addition to the mass number dependence of $\sigma_r$ for nucleons in the IQMD model calculation.