PNO-CI and CEPA studies of electron correlation effects. VI. Electron affinities of the first-row and second-row diatomic hydrides and the spectroscopic constants of their negative ions

Abstract

Near equilibrium potential curves for the ground states of the first-row and second-row diatomic hydride negative ions have been calculated using PNO-CI and CEPA wavefunctions. The spectroscopic constants for the bound AH− ground states are given and the Franck–Condon factors for the processes AH−→AH are derived. The calculated intensity ratios support fully the assignments of the photoelectron spectra but the shifts in the re values which have been deduced from the observed intensity ratios are shown to have the wrong sign in most cases. The calculated electron affinities show systematic errors ranging from−0.15 eV to −0.35 eV. The yet unobserved BH− and and AlH− are predicted to be stable with estimated affinities of about 0.15 eV.