REALISTIC MICROSCOPIC CALCULATIONS FOR THE LIGHT-NUCLEI A = 2 TO 7

The conventional theory of shell-model effective interactions encounte rs a divergence in its perturbation expansion owing to intruder states . By enlarging the model space to eliminate the core, and, hence, all core-polarization processes, we circumvent this problem. The perturbat ion expansion for the effective interaction can then be reasonably exp ressed in terms of only the Brueckner reaction matrix G in the no-core space plus all folded diagrams. The effective interaction for A = 2 i s simply the Brueckner G-matrix. For A > 2 exact results for the eigen energies are obtained, if the generalized, A-nucleon G matrix can be c onstructed. For A = 4 to 7, we approximate the A-nucleon G-matrix with the Brueckner G-matrix. Reasonable results can be obtained by treatin g the starting energy for the G matrix as a variable parameter to fix the binding energy.