Monopole and quadrupole interactions in binding energies of sd-shell nuclei

It is demonstrated by shell-model calculations of sd-shell nuclei that the binding energies are dominated by the monopole part of nucleon-nucleon interaction. The monopole component, which comes mainly from the two-body interaction in triplet-even channel, can be renormalized into one-body single-particle energies. It is also shown that the proton-neutron quadrupole interaction causes a sizable gain of binding energy by coherent configuration mixing of quadrupole deformation.