Dependence of the shell-model single-particle energies on different components of the nucleon-nucleon interaction - art. no. 014303

The spin-orbit splittings in the spectra of nuclei with mass numbers 5, 15, and 17 are studied within the framework of shell-model configuration mixin g calculations including 2 (h) over bar omega excitations. The contribution s of the two-body spin-orbit and tensor components of the nucleon-nucleon i nteraction are studied in various model spaces. It is found that the effect s of the two-body spin-orbit interaction are dominant and quite sensitive t o the size of the model space considered. The effects of the tensor interac tion are weaker. The correlations effects which are included in the larger (0+2) (h) over bar omega shell-model space reduce the spin-orbit splitting in the case of A =5 by 20%, and enhance it for A = 15 by about the same 20% . However, it is found that the correlations have a very small effect on th e d(3/2)-d(5/2) Splitting in A = 17.