A semiclassical, nonperturbative approach to the description of molecular collisions

Using the effective potential formulated by Rabitz [J. Chem. Phys. 57, 1718 (1972)], rotational energy transition probabilities for OCS molecules colliding with other OCS molecules are calculated by solving coupled Schrödinger equations under the classical straight line path approximation. These results are compared with similar transition probabilities calculated from second−order perturbation theory. The results are quite different for strong collisions. For weak collisions, the discrepancies are less for low values of J. On the basis of these results, qualitative explanations of rotational energy transfer for weak and strong collisions are offered.