A general procedure for the theoretical study of the Λ-doubling

Abstract

A perturbation matrix procedure for the theoretical study of Λ-doubling is suggested based on van Vlecks formalism. It is independent of Hund's coupling cases and yields directly the energy levels and wavefunctions in terms of perturber states. The procedure is applied to the X 2Π states of OH and SH whereby the perturbation matrix was constructed in the basis of large-scale multi-reference configuration interaction wavefunctions, which are computed for the X 2Π, A 2Σ+, B 2Σ+, 12Σ-, 2Δ and 4Σ- and 4Π states as a function of internuclear separation. In OH a splitting of 0·1591 cm-1 for the 2Π1/2(j = ½) state and 0·0521 cm-1 for the 2Π3/2(j = 3/2) state is calculated compared to the corresponding measured splittings of 0·1577 cm-1 and 0·0551 cm-1. For SH the corresponding splittings are 0·3062 cm-1 compared to the experimental value of 0·2814 cm-1 for the 2Π1/2 component and 0·0041 cm-1 compared to the measured value of 0·0035 cm-1 for the 2Π3/2 component. It is found that for large internuclear separations...