DIAGRAMMATIC APPROACH TO FREDHOLM PERTURBATION-THEORY

Fredholm perturbation theory (FPT) for bound states in quantum mechani cs may be expressed in terms of two basic types of diagrams. These dia grams, when combined according to a small number of rules, can be used to easily generate an arbitrary term in the perturbation series. We p resent here a derivation of these rules and a few examples to illustra te the application of FPT. The results obtained are generally better t han those calculated using Rayleigh-Schrodinger perturbation theory.