Vibrational spacings for H2+, D2+and H2

Abstract
New calculations are presented for the vibrational energy level spacings of the electronic ground states of H2 + and D2 + at the adiabatic level of approximation. A second-order perturbation method is used to find the non-adiabatic corrections to these spacings. The relevance of these results to the discrepancies between the observed and calculated vibrational spacings for H2 is discussed.