Valence and excited states of LiH^-

Valence and excited dipole-bound states of the LiH^- anion are calculated with the recently developed electron-attachment equation-of-motion coupled-cluster technique. It is found that the first dipole-bound state of LiH^- corresponds to the second dissociation channel LiH^-→Li^-(¹S)+H(²S). The second (excited) dipole-bound state of LiH^- is below the neutral ground-state potential energy curve only for some range of the Li-H internuclear distance. This state appears at bond lengths larger than ≈2.0Å and decays at Li-H distances longer than ≈4.2 Å, where the dipole moment of LiH becomes smaller than the critical value of 2.5 D. The adiabatic electron affinity of LiH calculated at the coupled-cluster level with the iterative inclusion of all single, double, and triple excitations and a large atomic natural orbital basis set is 0.327 eV, almost matching the recently obtained experimental value of 0.342±0.012eV.