ON THE ROLE OF 3RD-ORDER AND HIGHER-ORDER CONTRIBUTIONS TO THE EFFECTIVE INTERACTION FOR PF SHELL NUCLEI

In this work we have studied the inclusion of third- and higher-order contributions in perturbation theory to the effective interaction appropriate for the pf shell. We conclude that these contributions are important and ought to be carefully analyzed when approximating the effective interaction to a given order. To calculate the nuclear G-matrix we have employed a recent version of the Bonn meson-exchange potential model (potential A) and the Paris potential. We find the Paris potential to yield too little attraction, a result which agrees with findings in the sd shell. The Bonn A potential reproduces fairly well the data for most JT channels in the A = 42 system. For JT = 10 in the same mass system, however, too much attraction is introduced and the agreement with the data is poor. The implications are discussed.