State-to-state rate constants for rotational relaxation of CO in collisions with Ar: a quantum study

Abstract

Integral cross-sections and thermal rate constants for the CO( v=0, j) + Ar collisions are calculated within the coupled states method on two recent ab initio potential energy surfaces. The vibrationally elastic approximation is shown to provide an excellent agreement with three-dimensional quantum results whose sensitivity to the interaction potential is also examined. It is demonstrated that at j=0, both the energy corrected sudden scaling procedure and semiclassical method are unable to reproduce oscillations in the rotational product state distributions which is in accordance with recent benchmark close coupling calculations.