On the assignment of transitions involving some 2Π Rydberg states of the BeH molecule

Very accurate potential energy curves for several low-lying excited 2Π states of the BeH molecule are reported using the multireference configuration approach. New features in the potential energy curves of the B and G 2Π states not considered previously, like the existence of a double minimum, invalidate some of the arguments used in the assignment of transitions arising from these states. An alternative interpretation of some of the transitions and improved spectroscopic constants are presented. For the 3d states, for which experimental data are still uncertain about their nature, this study allows us to make an unambiguous correlation with the 3d 2Π state.