The electronic structure of CaO. II. An MCSCF/CI treatment of the low-lying 1Σ+ and 1Π states

State averaged multiconfiguration self-consistent field and configuration interaction methods are used to discuss the 1,2 1Σ+ states of CaO. Spectroscopic constants Re, Te, and ωe are determined. In addition, radiative transitions between the 1,2 1Σ+ states, and the 1 1Π states are discussed. The spectroscopic constants are in reasonable agreement with experiment although the predicted bond lengths are uniformly long. The calculated lifetime for the v=6 level of the A 1Σ+ state of 130×10−9 s is in good agreement with a preliminary experimental value. The lifetime of low-lying vibrational states in the A′ 1Π manifold are over an order of magnitude longer than their A state counterparts. The v=0 level of the A′ 1Π state is predicted to have a lifetime of 25×10−6 s.