A database for V-V state-to-state rate constants in N2-N2 and N2-CO collisions in a wide temperature range: dynamical calculations and analytical approximations

Extensive semiclassical calculations have been performed regarding the generation of accurate collision data for single-and multi-quantum vibrational state-selected V-V exchanges in N-2(v)-N-2(u) and N-2(v)-CO(u) collisions over a wide range of vibrational quantum numbers (v, u) and gas temperatures. This highly accurate database is also used to test the applicability of simplified analytical approximations frequently used in vibrational kinetic modeling to calculate large sets of state-to-state V-V rate constants in diatom-diatom collisions. The semiclassical calculations clearly show that the long-range attractive branch of the interaction potential cannot be neglected, even for the N-2-N-2 system. Therefore, new analytical approximations for V-V exchanges for the two collision systems are proposed which agree very well with the semiclassical rates. The ab initio data, together with that obtained from the newly proposed analytical formula, constitute an accurate database that can be used with confidence in the vibrational kinetic modeling of N-2 and CO-based gases and plasmas over a wide temperature range, from thermal to hyper-thermal gas temperatures.