Electronic structure and spectra of the lowest five 1Σ+ and 3Σ+ states, and lowest three 1Π, 3Π, 1Δ, and 3Δ states of NaK

We calculate the potential energy curves for all molecular states of NaK which may be obtained from the interactions Na(3s)+K(4s), Na(3s)+K(4p), Na(3p)+K(4s), Na(3s)+K(5s), Na(3s)+K(3d), and for the Δ states corresponding to the interactions Na(3d)+K(4s) and Na(4p)+K(4p) by full-valence configuration interaction computations which utilize effective core potentials to describe the core electrons, the core-valence orthogonality constraints, and the core-valence correlation (CVC) energy. The differences between our computed curves and those deduced from experimental spectra are generally small and can be accounted for by: (1) the modest size of the basis set, which is insufficiently diffuse to describe Na− and K− resonances associated with excited charge transfer interactions and related molecular Rydberg character, and (2) the approximate way in which the CVC interaction is included.