Theoretical study of stable negative ions of polar molecules: NaH−, LiH−, LiF−, BeO−

In order to investigate the nature of the binding of electrons to polar molecules, we have performed ab initio calculations on LiH, LiF, NaH, BeO, and their anions. The anions are predicted to be stable and our calculated vertical electron affinities of the parent molecules are 0.30, 0.46, 0.36, and 1.77 eV for LiH, LiF, NaH, and BeO, respectively. It is demonstrated that electron correlation effects are small in the binding of electrons to these polar molecules since the extra electron occupies a predominantly nonbonding orbital on the electropositive atom.