Existence of He2- negative ions with two remote electrons in antibonding orbitals

Calculations of low-lying quartet states of He2 - are reported, in which a positively charged core He2 + holds two remote electrons in antibonding orbitals, i.e. spending most time either side of and away from the central nodal plane, of similarly large RMS extent. A previously reported 4 u state is reinterpreted and shown to be a Rydberg state. Further, a 4 u state and a 4 g , the lowest state of this category, are reported. The calculation, performed in prolate spheroidal coordinates, is variational, utilizing one-electron diatomic-molecule-type orbitals, in full configuration interaction.

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