Microscopic linear response calculations based on the Skyrme functional plus the pairing contribution

TL;DR

This paper develops a self-consistent QRPA model based on the Skyrme functional and pairing interactions to study monopole excitations in spherical nuclei, analyzing the effects of pairing types and spurious states on resonance energies.

Contribution

It introduces a comprehensive QRPA approach incorporating various pairing forces and assesses their impact on monopole excitations and nuclear incompressibility.

Findings

Different pairing forces significantly affect the monopole strength function.

The model accurately predicts the ISGMR energies in tin isotopes.

Spurious states are effectively identified and separated from physical excitations.

Abstract

A self-consistent Quasiparticle-Random-Phase-Approximation (QRPA) model which employs the canonical Hartree-Fock-Bogoliubov (HFB) basis and an energy-density functional with a Skyrme mean field part and a density-dependent pairing, is used to study the monopole collective excitations of spherical even-even nuclei. The influence of the spurious state on the strength function of the isoscalar monopole excitations is clearly assessed. We compare the effect of different kinds of pairing forces (volume pairing, surface pairing and mixed pairing) on the monopole excitation strength function. The energy of the Isoscalar Giant Monopole Resonance (ISGMR), which is related to the nuclear incompressibility $K_{\infty}$, is calculated for tin isotopes and the results are discussed.