NO-CORE SHELL-MODEL CALCULATIONS WITH STARTING-ENERGY-INDEPENDENT MULTIVALUED EFFECTIVE INTERACTIONS

Large-space no-core shell-model calculations have been performed for H -3, He-4, He-5, Li-6, and He-6, using a starting-energy-independent tw o-body effective interaction derived by application of the Lee-Suzuki similarity transformation. This transformation can be performed by dir ect calculation or by different iteration procedures, which are descri bed. A possible way of reducing the auxiliary potential influence on t he two-body effective interaction has also been introduced. The many-b ody effects have been partially taken into account by employing the re cently introduced multivalued effective interaction approach. Dependen ce of the 5He energy levels on the harmonic-oscillator frequency as we ll as on the size of the model space has been studied. The Reid 93 nuc leon-nucleon potential has been used in the study, but results have al so been obtained using the Nijmegen II potential for comparison.