Spectroscopic properties and potential surfaces for atom-diatom van der Waals molecules

Abstract

A new method for calculating accurate spectroscopic constants for atom-diatom van der Waals molecules is presented. The method is based on the BOARS approximation of Holmgren et al. (1977, J. chem. Phys., 67, 4414), but does not neglect non-adiabatic corrections, which are shown to be significant. Molecular properties of Ar.. HCl are calculated for several proposed potential energy surfaces and compared with experiment. The centrifugal distortion of the nuclear quadrupole coupling constant is shown to be strongly potential-dependent. The computational cost of the full (non-adiabatic) treatment is similar to that of the original BOARS treatment.