Transition path sampling study of classical rate-promoting vibrations

The use of transition path sampling to study the classical rate-promoting vibrations was discussed. A complicated dynamical behavior that cannot be captured by transition state theory was found. It was observed that slow promoting vibrations lead to reactive trajectories that overshoot the saddle point, but on the other hand the short period of fast oscillations allows the reactants to stay only briefly in a low-barrier regime. It was shown that there is a competition between these effects, which results to an intermediate value for the frequency of the rate-promoting vibration that is optimal for enhancing the rate.