Quasi-classical model for vibrational-translational and vibrational-vibrational rate constants

We present the derivation and the numerical validation of new vibrational r ate constants for vibrational-translational and vibrational-vibrational pro cesses in a pure diatomic gas. The approach is based on the quasiclassical representation of the T matrix and the approximation of the multidimensiona l trajectories. For moderate temperatures, useful analytical formulas are p roposed. In the case of high temperatures, a numerical integration has to b e performed to compute numerical values of the rate-constants. The rate-con stant model proposed here is compared with the forced-harmonic-osciliator r ate model in a large temperature range and also with three-dimensional semi classical trajectory calculations for low temperatures (200 K less than or equal to T less than or equal to 8000 K), for nitrogen. The agreement is sa tisfatory.