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

Abstract

A study of the sensitivity of energy transfer efficiency in molecular collisions is reported with special focus on the hardness of repulsion in atom–atom contact. An improved pair potential is proposed with independent parameters for atomic size, attraction and hardness determined specifically for a chosen atom pair by supermolecular quantum chemistry or equivalent experimental interaction data. Colinear and full 3D collisions of atom–diatomic molecule 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 hardness than to attraction and (iii) suitability of MP2 energies in symmetry constrained axial directions as a data set for the determination of pair-potential parameters.