TDDFT with Skyrme Forces: Effect of Time-Odd Densities on Electric Giant Resonances

TL;DR

This paper investigates how time-odd densities influence electric giant resonances within the Skyrme functional framework, emphasizing the importance of current densities and effective-mass parameters in describing nuclear excitations.

Contribution

It demonstrates the significant role of time-odd densities, especially current densities, in accurately modeling electric giant resonances across various Skyrme forces and isotopes.

Findings

Current densities are essential for describing E1 and E2 resonances.

The contribution of current densities depends on the isovector and isoscalar effective-mass parameters.

The effects are consistent across different isotopes, including exotic nuclei.

Abstract

Time-odd densities and their effect on electric giant resonances are investigated within the self-consistent separable random-phase-approximation (SRPA) model for various Skyrme forces (SkT6, SkO, SkM*, SIII, SGII, SLy4, SLy6, SkI3). Time-odd densities restore Galilean invariance of the Skyrme functional, violated by the effective-mass and spin-orbital terms. In even-even nuclei these densities do not contribute to the ground state but can affect the dynamics. As a particular case, we explore the role of the current density in description of isovector E1 and isoscalar E2 giant resonances in a chain of Nd spherical and deformed isotopes with A=134-158. Relation of the current to the effective masses and relevant parameters of the Skyrme functional is analyzed. It is shown that current contribution to E1 and E2 resonances is generally essential and fully determined by the values and signs of the isovector and isoscalar effective-mass parameters of the force. The contribution is the same for all the isotope chain, i.e. for both standard and exotic nuclei.