The computation of nuclear motion and mass polarization adiabatic energy corrections for several states of the hydrogen molecule

This paper reports the computation of the diagonal matrix elements of the nuclear motion and mass polarization operators (often referred to as adiabatic corrections) for several electronic states of the hydrogen molecule. It is observed that reasonably simple wavefunctions will yield accurate expectation values for the nuclear motion operators. The present calculation covers a greater range of R for the X 1Σ+g and B 1Σ+u states than is covered in the very accurate work of Kolos and Wolniewicz, and includes computations for the C 1Πu and D 1Πu states for which no theoretical results have been previously reported. For the latter states the present diagonal corrections have been used in conjunction with the very recent Born–Oppenheimer potential energy curves of Kolos and Rychlewski [J. Mol. Spectrosc. 62, 109 (1976)] to compute vibrational level energies for both H2 and D2. The diagonal corrections largely remove the mass-dependent part of the discrepancy between theory and experiment for these vibrational level energies.