Accelerated Molecular Dynamics Study of Z/E Isomerization of Azobenzene: Kramers' Theory Validation

The reaction rate in a condensed phase is retarded by solvent friction and deviates from the transition state theory (TST) in a highly viscous solvent. The Z/E isomerization kinetics of 4-dimethylamino-4'-nitroazobenzene in solution have been experimentally analyzed in a wide range of pressure in our previous studies. Herein the non-TST behaviors of the rate constant were theoretically modelled by means of Kramers' theory and its extensions and by molecular dynamics (MD) simulations. The Z/E isomerization takes place in milliseconds or longer and so is not reachable by normal MD simulations. The accelerated MD method was employed to simulate the rare events using a biased isomerization potential barrier.