Density functional theory and molecular bonding. II. Alkali dimers

Binding energy curves for the 1Σ+g ground state of the alkali dimers Li2–Fr2 are calculated using the density functional formalism of Hohenberg, Kohn, and Sham. The resultant spectroscopic constants agree well with experiment and with MCSCF calculations for Li2 and Na2, in spite of the use of a local approximation for the exchange–correlation energy and of a ’’frozen-core’’ approximation. For each of the dimers, the 3Σ+u state is very weakly bound at a large internuclear separation.