Influence of Attractive Forces on the Quantum-Mechanical Transition Probabilities for Atom-Diatomic Oscillator Collisions

Abstract

Numerically exact quantum‐mechanical transition probabilities for the collinear collision between an atom and a diatomic oscillator interacting via a strongly attractive Morse potential are compared with those obtained in various simple perturbation approximations. It is concluded that many of the improved perturbation approximations which work well for purely repulsive interactions are also quantitatively accurate for Morse interactions having deeply attractive wells. A simple distorted wave correction factor, derived, for example, via second‐order perturbation theory, yields quite accurate transition probabilities, even for very small reduced collision energies (E_coll/D=0.05) where attractive forces dominate in determining the dynamics of the collision. Furthermore, when the perturbation limit is no longer applicable, the so‐called exponential approximation provides a viable method for calculating both direct and multiquantum transition probabilities.