Improved Perturbation Theory for Inelastic Encounters

Abstract

An improved perturbation theory for inelastic bimolecular collisions is proposed, which is based upon the suitable choice of an effective distortion potential derived from a second‐order adiabatic optical potential. Since the new theory involves simply a rescaling of the original effective interaction, essentially no additional labor is required to obtain the corrected transition probabilities, at least for the special case of a one‐dimensional problem. For example, an application to the prototype problem of vibrational relaxation, namely the collinear collision of an atom with a harmonic oscillator, reduces the error of the usual distorted wave approximation from 116% to 5%, averaging over all cases for which exact multistate results exist for comparison. Furthermore, a simple prediction concerning the accuracy of the distorted wave approximation for resonance transitions is borne out by exact results.