Theoretical studies on N = Z nuclei in the 2s--1d shell

Employing the unitary-model operator approach of Shakin, Waghmare, Tomaselli, and Hull and two realistic nucleon--nucleon potentials, one a modified version of the Yale potential adjusted to yield a lower percentage of the ''D''-state in the deuteron ground state without affecting the other two-nucleon quantities calculable from the Yale potential, and the other a super-soft core potential published by de Tourreil and Sprung, the ground-state properties of the even--even N = Z nuclei are calculated, for the 2s-1d shell, using the Hartree-Fock self-consistent approach. These results are compared with similar but less sophisticated calculations published earlier. The effect of introducing the T = 0 and T = 1 pairing correlations is also examined within the framework of the generalized BCS (Bardeen-Cooper, Schrieffer) approach, with a view to study the effect of the variation of the tensor force in the Yale two-nucleon interaction on the n-p, p-p, and n-n correlations. Such a study also provides an additional test of the super-soft core potential and renders the opportunity to evaluate its overall performance in nuclear structure calculations against those employing realistic interactions with hard-core features. Shell-model spaces of various sizes are used in the present calculations. First, the limited model space spanning all the single-particle levels up to and including the 2s-1d shell, as used by Nisley and Hull, as well as by Goodman, are employed to enable one to make direct comparison with their results. Later on exhaustive calculations, including the 0f-1P and higher shells (up to the 3s/sub 1/2/ level) in the expansion basis, are carried out