Implementation of the quasiparticle finite amplitude method within the relativistic self-consistent mean-field framework: The program DIRQFAM

Abstract

The DIRQFAM code calculates the multipole response of even–even axially symmetric deformed nuclei using the framework of relativistic self-consistent mean-field models. The response is calculated by implementing the finite amplitude method for relativistic quasiparticle random phase approximation. Program summaryProgram Title:DIRQFAMProgram Files doi:http://dx.doi.org/10.17632/6gv8nxg4ns.1Licensing provisions: GPLv3Programming language: Fortran 90/95, easily downgradable to FORTRAN 77.External routines/libraries: BLAS/LAPACK, version 3.6.0. or higher.Nature of problem: Multipole response of deformed even–even open-shell nuclei can be calculated using the quasiparticle finite amplitude method (QFAM), based on the relativistic self-consistent mean-field models. The particle–hole channel is described by a zero-range relativistic effective interaction, while the particle–particle channel of the effective inter-nucleon interaction is described by a separable finite-range pairing force. The method can be applied to perform systematic studies of collective modes even in heavy deformed nuclei.Solution method: The current implementation computes the multipole response by solving the QFAM equations in a self-consistent iteration scheme. At each iteration the QFAM solutions are updated using the modified Broyden’s method. The QFAM amplitudes are expanded in the simplex-y harmonic oscillator basis.Restrictions: Open-shell even–even nuclei with axially symmetric ground states are considered. An electric multipole operator with J≤3 is used to calculate the response function.Unusual features: The code should be recompiled before running it with different values of one of the following input parameters: number of oscillator shells in the expansion of nucleon spinors (n0f), number of Gauss–Hermite (NGH) or Gauss–Laguerre nodes (NGL), the multipolarity values that define the external perturbation operator (J_multipole, K_multipole).