The parameters of the interacting boson model are calculated in a shell model framework, using a generalized seniority basis. The effect of the neutron-proton interaction on the $s$- and $d$-boson structure is explicitly considered. The renormalization due to the truncation of the full fermion space to the $S-D$ subspace is considered by taking the effects of the $G$-pair state into account using perturbation theory. It is found that this effects mainly the single boson energies and introduces a Majorana force that favors states symmetric in neutron and proton degrees of freedom over antisymmetric ones.

NUCLEAR STRUCTURE Microscopic calculation of interacting boson approximation parameters. Shell model calculations in the generalized seniority basis.

• Received 9 June 1983

DOI:https://doi.org/10.1103/PhysRevC.28.1783