Threshold behaviour of different collisional models for vibration-translation energy transfers in gases

We recently developed the so-called classical-discrete (CD) fluctua¬tion model for inelastic molecular collisions, and as a first application of the model equations we investigate in this paper the case of vibrational-energy transfer between molecules occurring during a collision led by a repulsive-exponential potential. CD results are here compared with previous available equations given by classical mechanics - also when improved with the Zener symmetrization rule - and by quantum mechanics. The paper shows that using the CD result considerably improves the classical mechanics possibilities to treat the process in hand and that the threshold properties of the inelastic effect are correctly displayed by the fluctuation model equation.