Calculations of electron affinities of first-row atoms

Abstract

Electron affinities are computed in a modified variational approximation for the ground states of B, C, N, O, and F. The method augments the variational basis for the neutral-atom wave function to include all configurations defined by open-shell virtual excitations that are implicit in the basis used for the negative ion. This basis is generated, as in electron-scattering calculations, from a specified list of neutral-atom configurations, by adjoining all available unoccupied or partially occupied orbital functions. The neutral-atom basis includes configurations defined by the first-order perturbing wave function for electric dipole polarizability. When single-particle virtual excitations $2s\to \overline{s}$, $2s\to \overline{d}$, $2p\to \overline{p}$ are included, results are close to experiment, with errors from 0.02 to 0.20 eV.