Inelastic scattering calculations in polyatomic systems using an a b i n i t i o intermolecular potential energy surface. II. Rotational energy transfer in CO2–H2 collisions

Results of quasiclassical trajectory studies of CO2 (Ji=0, 16, 30)–H2 (Ji=0, 2) collisions at Etot=0.1, 0.2 eV are reported in terms of state-to-state integral inelastic cross sections, first moments of energy transferred in excitation and de-excitation processes and C values which characterize the variation of the rotational suprisal with energy gap between initial and final states. The magnitude of the first moments are shown to increase with increasing translational energy Ti and with the initial rotational state JiCO2. The value of C decreases with increasing Ti. It is found to be strongly dependent upon JiCO2 but depends only weakly upon JiH2. Comparison of our results with those of Preston and Pack for the CO2–He and CO2–Ar systems reveals that although the qualitative dependence of σ−, σ+, σ, 〈ΔE−〉 and 〈ΔE+〉 upon Ti and JiCO2 is the same in all three systems, there are quantitative differences which reflect the atomic (molecular) size of He, H2, and Ar. Furthermore, the suprisal parameter is distinctly different for all three collision partners (decreases in the order H2, He, Ar) even when the ’’linear sum rule’’ holds, contrary to an earlier proposal by Procaccia and Levine that the surprisal parameter C would be independent of the nature of the collision partner.