Shell-model study of boron, carbon, nitrogen, and oxygen isotopes with a monopole-based universal interaction

We study boron, carbon, nitrogen, and oxygen isotopes with a newly constructed shell-model Hamiltonian developed from a monopole-based universal interaction (V-MU). The present Hamiltonian can reproduce well the ground-state energies, energy levels, electric quadrupole properties, and spin properties of these nuclei in full psd model space including (0 - 3)(h) over bar omega excitations. Especially, it correctly describes the drip lines of carbon and oxygen isotopes and the spins of the ground states of B-10 and N-18 while some former interactions such as WBP and WBT fail. We point out that the inclusion of 2 (h) over bar omega excitations is important in reproducing some of these properties. In the present (0 + 2)(h) over bar omega calculations small but constant E2 effective charges appear to work quite well. As the inclusion of the 2 (h) over bar omega model space makes a rather minor change, this seems to be related to the smallness of the He-4 core. Similarly, the spin g factors are very close to free values. The applicability of tensor and spin-orbit forces in free space, which are taken in the present Hamiltonian, is examined in shell-model calculations.