Density functional theory of autodetaching states

The authors consider the application of ab initio single-configuration orbital theories to predict the existence and energies of autodetaching states or resonances in atoms and molecules. Numerical results are given for the (ns)2 resonances in H- and He. In some cases (e.g. He) the conventional orbital theories (either Hartree-Fock or the local spin density approximation for exchange and correlation) give useful results, but the important autodetaching states of negative ions are usefully described only by the new self-interaction-corrected (SIC) version of the local spin density approximation. The authors also discuss how a (1s)2 resonance appears and then disappears in a two-electron ion as the nuclear charge Z is reduced below 1. The SIC calculation for this system displays an analogue to the 'bound state in the continuum' which Stillinger (1966) found for Z approximately=0.9.