Canonical-basis time-dependent Hartree-Fock-Bogoliubov theory and linear-response calculations

TL;DR

This paper introduces a simplified canonical-basis formulation of the time-dependent Hartree-Fock-Bogoliubov theory, reducing computational costs and enabling accurate linear-response calculations for light nuclei.

Contribution

The authors develop a new canonical-basis approach to TDHFB that simplifies equations by assuming a diagonal pair potential, improving computational efficiency for nuclear response studies.

Findings

Accurate E1 strength distributions for Ne and Mg isotopes.

Systematic analysis of pygmy strength evolution with nuclear properties.

Validation against quasi-particle RPA calculations.

Abstract

We present simple equations for a canonical-basis formulation of the time-dependent Hartree-Fock-Bogoliubov (TDHFB) theory. The equations are obtained from the TDHFB theory with an approximation that the pair potential is assumed to be diagonal in the canonical basis. The canonical-basis formulation significantly reduces the computational cost. We apply the method to linear-response calculations for even-even light nuclei and demonstrate its capability and accuracy by comparing our results with recent calculations of the quasi-particle random-phase approximation with Skyrme functionals. We show systematic studies of E1 strength distributions for Ne and Mg isotopes. The evolution of the low-lying pygmy strength seems to be determined by the interplay of several factors, including the neutron excess, separation energy, neutron shell effects, deformation, and pairing.