Electron affinity calculations on NH−2, PH−2, CN−, SH−, OH−, Cl−, and F−: Basis sets and direct vs indirect methods

Electron affinities are calculated with fourth order many-body perturbation theory. Comparisons with renormalized, quasiparticle propagator calculations with the same or comparable basis sets are emphasized. Basis set improvements, including multiple polarization functions, have a great effect on the post-SCF results. The best calculated electron affinities (in eV) and the corresponding experimental values in parentheses are as follows: NH2 0.707 (0.779±0.037), PH2 1.160 (1.271±0.010), SH 2.223 (2.319±0.010), OH 1.764 (1.825±0.002), Cl 3.526 (3.615), and F 3.369 (3.399). Problems with the CN calculations are discussed. Implications of this work for studies of larger systems concern basis set choices and methods of treating electron correlation.