Classical Study of Rotational Excitation of a Rigid Rotor: Li+ + H2

Abstract

Classical calculations are presented for a model problem simulating the rotational excitation of H2 (and D2) in collision with Li+, based upon the ab initio potential surface of Lester. The hydrogen molecule was taken to be a rigid rotor, even though this assumption becomes progressively worse as the collision energy is increased and the vibrational excitation threshold is crossed. However, the results should serve as a set of reference calculations on a well-defined system, suitable for comparison with semiclassical and quantal treatments. The influence of initial rotational state, molecular mass, and collision energy upon the angular distribution of the average rotational energy transfer and total inelasticity is evaluated and discussed. Most of the trends are due to simple dynamical effects and they also occur in computations using a rigid ellipsoid model for the diatomic molecule.