The ionization potentials, electron affinities, and term splittings of the lowest electronic configurations for first-row atoms for $Z$ from 5 to 10 have been computed. The method used is that applied previously to ground-state correlation energies. Variational calculations equivalent to solution of one- and two-particle Bethe-Goldstone equations are carried out, following approximate Hartree-Fock calculations for each state of each atom or ion considered. Computed quantities are in reasonably good agreement with experiment. Bethe-Goldstone equations as used here are defined in terms of individual orbital excitations. Calculations of three-particle effects are included in some cases, computed with less relative accuracy than the other results. The three-particle terms are not negligible. In particular, they substantially reduce the magnitude of computed electron affinities.

• Received 21 May 1971

DOI:https://doi.org/10.1103/PhysRevA.4.1336