Method for atomic calculations.

Abstract

Truncated Taylor-series representations of ${r}_{12}^{\mathrm{\ensuremath{-}}1}$ yield a variety of resummation alternatives to the corresponding Legendre expansion defining a basis-set--dependent Hamiltonian which allows a faster harmonic convergence of orbital methods. In this way, configuration interaction calculations of He, Li, and Ne ground-state energies converge to within a major fraction of the correlation energy with considerably less effort.