Vibration-rotation relaxation in bimolecular collisions with application to para-hydrogen

Three-dimensional quantum mechanical calculations in the effective potential approximation have been made on the para-hydrogen system. At low temperatures, vib-rotationally inelastic collisions were examined while breathing sphere calculations were used to probe the high-temperature regime. It was found that simultaneous vibrational and rotational processes contribute to the overall mechanism of vibrational relaxation. Collisionally induced intra- and intermolecular energy transfer is possible in the present calculation, and the corresponding cross sections are examined in detail. Rates are calculated from the cross sections and compared with experiment.