2023 APS Fellow. Talk Title: Transition State Theory for Nonequilibrium Kinetics: Comparisons with Quasiclassical Trajectories

We consider the applicability and accuracy of bimolecular transition state theory (TST) for cases where the reactants are not in equilibrium with each other. Despite its simplicity, TST has proven itself to be both a means of generating quantitative rate constants as well as the basis of a useful chemical intuition connecting transition state structures with mechanistic insights. In TST, there is an implicit assumption that the transition state is populated according to the same equilibrating assumption as both reactants. When the reactants are not in equilibrium with each other, different assumptions must be made. We derive and test the accuracy of a multi-temperature TST for nonequilibrium kinetics that retains the simplicity of conventional TST. Tests of its accuracy are made via comparisons with quasiclassical trajectories for the kinetics of CH₄ + H, O, and OH, for H₂O + H and O, and for H + HO₂.