Symmetry-Adapted Pair Correlations in Ne,F−,Ne+, and F

The superposition-of-configurations method has been used to calculate, a single pair at a time, the pair correlation energies for Ne, ${\mathrm{Ne}}^{+}$, ${\mathrm{F}}^{-}$, and F. The approach is essentially a symmetry-adapted variation of Nesbet's formulation of the Bethe-Goldstone scheme for the atomic correlation problem, and the aim of this research was to test the usefulness of the method for predicting such physically observable quantities as ionization potentials and electron affinities. The calculations predict an ionization potential for neon of 21.52 eV, compared with a 21.56-eV experimental value, and a fluorine electron affinity of 3.47 eV, for which the experimental value is 3.45 eV.