Coulomb and spin-orbit interactions in random-phase approximation calculations

Abstract

We present a fully self-consistent computational framework composed by Hartree-Fock plus random-phase approximation where the spin-orbit and Coulomb terms of the interaction are included in both steps of the calculations. We study the effects of these terms of the interaction on the random-phase approximation calculations, where they are usually neglected. We carry out our investigation of excited states in spherical nuclei of oxygen, calcium, nickel, zirconium, tin, and lead isotope chains. We use finite-range effective nucleon-nucleon interactions of Gogny type. The size of the effects we find is, usually, of a few hundred keV. There are not simple approximations which can be used to simulate these effects since they strongly depend on all the variables related to the excited states, angular momentum, parity, excitation energy, isoscalar, and isovector characters. Even the Slater approximation developed to account for the Coulomb exchange terms in the Hartree-Fock approximation is not valid in random-phase approximation calculations.