Answers are grounded in this paper and cite their sources.
The quasi-degenerate Rayleigh-Schrödinger perturbation theory (QD-RSPT) proposed by Brandow [3] is rederived in matrix form. An approximate computational method is proposed which includes the diagonal energy renormalizations (the diagonal folded diagrams) to infinite order. Several numerical examples are presented which illustrate the numerical stability of the method.
No takes yet. Share an insight, caveat, or question.
Hegarty et al. (1979) studied this question.
Synapse has enriched 10 related papers. Consider them for comparative context: