3RD-ORDER TREATMENT OF THE ONE-BODY EFFECTIVE INTERACTION

All terms through third order in the reaction matrix that contribute to the one-body effective interaction of 17O are evaluated using an accurate, energy-dependent reaction matrix. The thirdorder terms are respectably small compared to the second-order terms. The three-particle two-hole (3p2h) terms give a uniform repulsion of about 1 MeV with little influence on the excitation spectrum. As a result, the 0d 5 2, 1s 1 2 and 0d 3 2 valence energies are in reasonable agreement with the experimental excitation energies as found earlier with a (1p + 2plh) all-orders approach. However, the absolute energy is now about 2 MeV too repulsive. © 1979.