Independent-particle models for light negative atomic ions

For the purposes of astrophysical, aeronomical, and laboratory application, we seek a precise independent-particle model for electrons in negative atomic ions of the second and third period. The optimum-potential model (OPM) of Talman et al. is first used to generate numerical potentials for eight of these ions. Results for total energies and electron affinities are found to be very close to Hartree-Fock solutions. However, the OPM and HF electron affinities both depart significantly from experimental affinities. For this reason we develop two analytic potentials whose inner energy levels are very close to the OPM and HF levels but whose last electron eigenvalues are adjusted precisely with the magnitudes of experimental affinities. These models are (1) a four-parameter analytic characterization of the OPM potential and (2) a two-parameter potential model of the Green, Sellin, Zachor type. The system O^- or e-O, which is important in upper atmospheric physics is examined in some detail.