Nonadiabatic eigenvalues and adiabatic matrix elements for all isotopes of diatomic hydrogen

For all bound and quasibound levels of the ground electronic state of all six isotopes of diatomic hydrogen, wavefunctions obtained from the most recent ab initio potentials are used to calculate expectation values of the nuclear kinetic energy, of various powers of R, and of the average polarizability and polarizability anisotropy, together with the off-diagonal matrix elements of the polarizability required for predicting the intensities of Raman transitions for ΔJ = 0, ±2 and Δv = 0, -1, and -2. A scaling procedure for treating the nonadiabatic eigenvalue corrections is developed, which allows an extrapolation beyond results reported for H₂, HD, and D₂ to yield nonadiabatic level shift predictions for the three tritium isotopes. Features of this procedure which take account of implicit centrifugal distortion effects lead to significant improvements in the agreement between theory and experiment.