First-Order Wavefunctions, Orbital Correlation Energies, and Electron Affinities of First-Row Atoms

The most strongly structure-sensitive part of the correlation energy of an atomic state (called here the orbital correlation energy) may be calculated using a configuration-interaction function we call the first-order wavefunction. First-order wavefunctions and orbital correlation energies are presented for all low-lying electronic states of B, C, N, O, F, Ne, and their positive and negative ions. These data provide ab initio ionization potentials and electron affinities for the atoms involved, which are used in conjunction with available experimental data to make estimates of unmeasured electron affinities to a probable accuracy of ± 0.10 eV. The results indicate the 3P ground state of B− to be stable by 0.187 eV, while predicting the instability of N− (3P) and the metastability of N−(1D) and N−(1S). In apparent disagreement with the conclusions of Seman and Branscomb, C−(2D) is predicted to be unstable relative to C(3P).