Inclusion of core-valence correlation effects in pseudopotential calculations. II. K₂and KH lowest Σ⁺potential curves from valence-correlated wavefunctions

For pt.I see J. Chem. Phys., vol.77, p.3571 (1982). The recently proposed perturbative treatment of core-valence correlation effects is extended to valence correlated wavefunctions. As expected, the valence correlation slightly diminishes the core-valence correlation for the ground state. This effect is illustrated for the atomic electron affinity of K. The core-valence correlation plays a very important role in the spectroscopy of K 2 and KH, where it increases the lowest X 1 Sigma + to A 1 Sigma + transition energies by 2300 and 1100 cm -1 , respectively.