SUMMATION OF TIME-DEPENDENT FOLDED DIAGRAMS FOR EFFECTIVE INTERACTIONS WITH A NONDEGENERATE MODEL SPACE

We analyze the diagrammatic structure of the effective interaction for the case of a non-degenerate model space. A time-dependent folded-dia gram formulation is used. It is found that the valence-linked time-ord ered diagrams contained in such effective interactions can also be exp ressed in terms of the multi-energy (Q) over cap-boxes of the form and , (Q) over cap(n) (epsilon(1) epsilon(2)...epsilon(n+1)), which were i ntroduced by Suzuki et al. for a time-independent description of the e ffective interaction. A partial-fraction method for the evaluation of the multi-energy (Q) over cap box, in terms of valence-linked diagrams , is discussed. A generalized Krenciglowa-Kuo iteration method for sum ming up the folded-diagram series is also designed. A schematic model is solved to compare the non-degenerate theory with the usual degenera te theory. It is shown that the present approach makes a distinct impr ovement in the calculation of effective interactions.