Reversible chemical reactions in slowly relaxing environments: Kramersʹ turnover of the rate constant Original Research Article

The turnover behavior of the rate constant as a function of the friction coefficient of the chemical mode is studied in a slowly relaxing environment/solvent. In rapidly adjusting environments, the turnover problem has been solved by Melʹnikov and Meshkov. The reaction dynamics is studied with a special focus on the influence of long-distance recrossings. Such recrossings take place when the potential of mean force along the chemical coordinate has a double-well structure. Two kinds of the turnover behavior have been discovered. When the relaxation is not too slow, the turnover is not accompanied by variation of the activation energy of the rate constant like in a fast environment. However, when the relaxation is slow enough, a significant decrease of the activation energy accompanies the turnover.