T=0 effective interaction in the sd shell

Abstract

A simple model interaction for T=0 two-nucleon states in sd shell nuclei is described. All the two-body matrix elements are expressed in terms of seven radial matrix elements (which later effectively reduce to three) as in an earlier paper. The values of the parameters are obtained by making a least-squares fit to observed level energies in ¹⁸F and ¹⁹F and are then used to calculate the level schemes of ²⁰F and ²⁰Ne. The parameters and the spectra obtained here are compared with those calculated from realistic nucleon-nucleon forces. Such simple interaction forms are used here may be particularly valuable in assessing the sensitivity of shell-model results to the use of specific interactions or to truncations of the basis space or the like.