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
In chemistry, transition state theory (TST) explains the reaction rates of elementary chemical reactions. The theory assumes a special type of chemical equilibrium (quasi-equilibrium) between reactants and activated transition state complexes.
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(TST) are also used in NA-TST but with some corrections. First, a spin-forbidden reaction proceeds through the minimum energy crossing point (MECP) rather than through transition state (TS).
Second, unlike 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 is a driving force 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.
References
Chemical physics
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