Pair-potential model for simulation of collisional energy transfer: quantum effects and hardness dependence

A study of the sensitivity of energy transfer efficiency in molecular colli sions is reported with special focus on the hardness of repulsion in atom-a tom contact. An improved pair potential is proposed with independent parame ters for atomic size, attraction and hardness determined specifically for a chosen atom pair by supermolecular quantum chemistry or equivalent experim ental interaction data. Colinear and full 3D collisions of atom-diatomic mo lecule collisions are simulated using classical or quantum (in the colinear case) mechanics to illustrate: (i) remarkable agreement between classical and quantum dynamics for V-T energy transfer; (ii) greater sensitivity to h ardness than to attraction and (iii) suitability of MP2 energies in symmetr y constrained axial directions as a data set for the determination of pair- potential parameters.