A theoretical treatment of the (A)over-tilde(2)Sigma(+) state of the Ar center dot center dot center dot HS/Ar center dot center dot center dot SH van der Waals complex

We present an ab initio potential energy surface for the à 2Σ+ state of the Ar⋯⋯HS van der Waals molecule. The surface represents a fit to 196 points calculated at the RCCSD(T) level with an aug-cc-pV5Z basis set and encompasses both the Ar⋯SH and Ar⋯HS isomers. We have further calculated vibrational levels on this surface using a discrete variable representation (DVR) approach. The vibrational levels supported within the Ar⋯HS minimum are compared with levels derived from high-resolution laser induced fluorescence spectra. Predictions of vibrational levels for the Ar⋯SH isomer, which have not been observed experimentally, are also presented