Static dipole polarizability of the lithium atom, cation, and anion

All-electron configuration-interaction calculations for the species Li, ${\mathrm{Li}}^{+}$, and ${\mathrm{Li}}^{-}$ in the presence of a distant negative charge (of charge -1) have been performed and, from the energies, the ground-state static dipole polarizabilities have been determined. The results (in atomic units) for Li and ${\mathrm{Li}}^{+}$, 164 and 0.188, respectively, are in good agreement with earlier predictions based on other methods. For ${\mathrm{Li}}^{-}$ we find that electron correlation practically halves the value of the dipole polarizability, reducing it to 650; previous values have ranged from 800 to 1910. In addition, for purposes of comparison and as a prelude to future calculations on small lithium clusters, we have carried out a valence-electron calculation (using a pseudopotential for the two core electrons) for the neutral atom; the results indicate that for lithium species core-core and core-valence electron correlation does not significantly affect the polarizability.