Spectroscopy and thermodynamics of LiS/NaS (X2Π and A2Σ+) and LiS+/NaS+(X3Σ− and A3Π)

Potential energy curves are calculated for the X2Π and A2Σ+ states of LiS and NaS and the X3Σ− and A3Π states of LiS+and NaS+. The RCCSD(T)/aug-cc-pVXZ levels of theory are employed (X = Q, 5 and ∞), where the ∞Z results are obtained at each bond distance, R, employing a two-point extrapolation to the basis set limit. From the three sets of curves, spectroscopic constants, ionization and dissociation energies are derived. Comparison is made to available experimental and calculational results.