The radial Hamiltonian operator for LiH X1Σ +

Abstract

Precise data for rotational and vibration-rotational transitions involving low-lying X 1Σ + vibrational levels of 6LiH, 7LiH, 6LiD, and 7LiD are employed simultaneously in a least-squares procedure for determination of the radial Hamiltonian operator for nuclear motion. Synthetic line positions from eigenvalues obtained by numerical solution of the Schrödinger equation with the fitted Hamiltonian are in agreement with the experimental data to within the measurement accuracies. The equilibrium separation R e of the Born-Oppenheimer potential is in close agreement with several previous estimates that take account of Born-Oppenheimer breakdown effects. The results obtained for the Born-Oppenheimer potential, as well as the associated radial functions that describe homogeneous and heterogeneous mixing, supercede the set of functions derived by J. F. Ogilvie ( J. Mol. Spectrosc. 148, 243–249 (1991) using an algebraic method, which are now known to be in error. It has not yet been established that eigenvalues of an algebraically determined operator can generate line positions that are in agreement with experimental positions to within the measurement uncertainties.