R-Matrix Expansion for the Ground-State Energy of a Many-Fermion System

Abstract
The R-matrix expansion for the ground-state energy of a many-fermion system is carried through fourth order. We evaluate this expansion for a potential modeled after the nucleon-nucleon one. The calculation is described in detail. We find that the "hole-line" approximation seems to underestimate the attraction so that a hard-core force may well be consistent with the experimental binding energy of large nuclei.