Nonadiabatic transition state theory

Nonadiabatic transition state theory (NA-TST) is a powerful tool to predict rates of chemical reactions from a computational standpoint. NA-TST has been introduced in 1988 by Prof. J.C. Lorquet. In general, all of the assumptions taking place in traditional transition state theory (TST) are also used in NA-TST but with some corrections. Firstly, the assumption that the reaction proceeds through the TS is replaced by a new one when TS is replaced by minimum energy crossing point (MECP). Secondly, by contrast with TST, the probability of transition is not equal to unity during the reaction and treated as a function of internal energy associated with the reaction coordinate. At this stage non-relativistic couplings responsible for mixing between states affect the probability of transition. For example, the larger spin-orbit coupling at MECP the larger the probability of transition. NA-TST can be reduced to the traditional TST in the limit of unit probability.