Theoretical Electronic Transition Probabilities in Diatomic Molecules. I. Hydrides

Hartree–Fock (HF) electronic transition moments calculated in both the position and momentum representations are presented as a function of the internuclear separation $R$ for the BeH, MgH, OH, and SH $\mathrm{(A–X)}$ systems. The vibrational averages of these quantities are obtained and the results are used to calculate some absorption band oscillator strengths. For the OH $\mathrm{(A–X)}$ system several independent experimental determinations of the 0–0 band oscillator strength have been reported in the literature. Our theoretical value of 20.6 × 10⁻⁴ differs from experiment by a factor of 2.5. Active electron and virtual orbital approximations to the HF transition moment integrals are given. Consideration of the united and separated atom limits and the region of the equilibrium internuclear separation for the states involved leads to an abbreviated discussion of the effect of correlation on the HF transition moments. HF transition moment calculations at a single value of $R$ are also reported for the BH⁺, AlH⁺, HF⁺, and HCl⁺ $\mathrm{(A–X)}$ systems.