Large-basis shell model studies of light nuclei with a multivaluedG-matrix effective interaction

Large-basis shell model studies of low-lying excitations in light nuclei from ${}_{}{}^4{}_{}{}^{}\mathrm{He}$ to ${}_{}{}^7{}_{}{}^{}\mathrm{Li}$ have been performed with a multivalued G-matrix effective interaction, as recently suggested by Haxton et al. Calculations were performed relative to the vacuum (‘‘no core’’) using very large, separable model spaces containing all excitations with unperturbed energies up to 8ħΩ. Using G matrices derived from a new Nijmegen potential, we achieve a very satisfactory description of these excitations.