Classical analysis of intermolecular potentials for Ar-CO2 rotational collisions

Classical trajectory calculations have been performed for four potential en ergy functions to describe Ar-CO2 collisions. A comparison is given between classical cross sections calculated using the two most recent potential su rfaces and two older intermolecular potential surfaces based on the electro n gas model. The two-dimensional atom ellipsoid model has also been applied for the study of multiple collisions. The model was able to predict such a phenomenon in agreement with quantum scattering results previously publish ed for an ab initio potential surface in the region of very low collision e nergy. On the other hand, the two older potentials showed multiple collisio n effects at very high energies. The comparison of the cross sections showe d some deviations from the experimental data. By introducing two parameters , a modified surface is proposed by changing the most recent intermolecular potential. In this case the agreement with experimental measurements and t heoretical scattering cross sections was considerably improved. It is concl uded that global potential surfaces for describing Ar-CO2 interaction are n ot well established. To achieve the requirement of reproducing all properti es of this system, the present work suggests that one needs further experim ental and theoretical investigations.