Internal energy transfers in molecular collisions

The theoretical and computational methods recently applied to the quantum mechanical calculation of various types of inelastic cross sections, those that preside over the transfer of kinetic energy into rotovibrational molecular modes, are reviewed and discussed. Ab initio methods to obtain the necessary potential energy surfaces (PES) are presented and their effectiveness shown in a few specific cases. The coupled representations in the space-fixed (SF) and Body- fixed (BF) frames of reference are used to expand the total wave- functions; the corresponding close coupled (CC) equations are also presented. Decoupling methods that are aimed at reducing the fast-growing dimensions of the above rigorous equations are also summarized and discussed, together with the most recent numerical techniques employed to solve these equations and to yield the corresponding S-matrix elements. A large bibliography has been selected from the very rich, recent literature on this expanding subject