Combined fitting of optical and millimeter wave data: The linked A2Π-X2Σ+ and B2Σ+-X2Σ+ systems of Ca79Br and Ca81Br

Adiabatic corrections to the Born-Oppenheimer potential energy curve for the $\text{B″}{}^1\text{Σ}{}_{\mathrm{u}}{}^{\mathrm{+}}$ state of the hydrogen molecule has been computed using a 60-term variational wavefunction in the form of an expansion in elliptic coordinates and depending explicitly on the interelectronic distance. For three internuclear separations new Born-Oppenheimer energies are also given which represent corrections of the previously published values. For H₂ the adiabatic correction to the dissociation energy amounts to 57.5 cm^?1. The computed dissociation energies for H₂, HD, and D₂ are by 23–25 cm^?1 smaller than the experimental values, the discrepancy being probably due to the convergence error of the Born-Oppenheimer potential. A few lowest vibrational levels and vibrational quanta have been calculated for H₂, HD and D₂, and compared with the experimental results.