Rotationally inelastic collisions of LiH with He: Quasiclassical dynamics of atom-rigid rotor trajectories

Rotationally inelastic cross sections for the LiH--He collision system are computed classically using a previously derived ab initio potential energy surface [D. M. Silver, J. Chem. Phys. 72, 6445 (1980)]. The LiH is in its ground vibronic state and is initially taken to be in its j = 1 rotational state. The He is in its ground electronic state. The system is treated as an atom-rigid rotor interaction. The results are compared with previously computed cross sections derived from the same ab initio potential energy surface using the coupled states approximation for quantum mechanical scattering [E. F. Jendrek and M. H. Alexander, J. Chem. Phys. 72, 6452 (1980)]. The theoretical total cross sections are averaged over a temperature distribution and are then compared with experimental measurements of corresponding cross sections for a rotationally resolved LiH beam ( j = 1) incident on a He gas target in thermal equilibrium at room temperature [P. J. Dagdigian and B. E. Wilcomb, J. Chem. Phys. 72, 6462 (1980)]. The agreement between classical, quantum and experimental results is discussed