Controlling reaction dynamics in chemical model systems through external driving

TL;DR

This paper demonstrates that external driving can control and enhance chemical reaction rates by affecting the transition state dynamics, with implications for reaction probability manipulation.

Contribution

It reveals how external driving influences the transition state and reaction rates in a model system, introducing bifurcations and trajectory changes that can be harnessed for reaction control.

Findings

External driving can create a local maximum in the decay rate.

Bifurcations of periodic trajectories occur on the transition state manifold.

Reaction probabilities can be modulated through external driving.

Abstract

The rate of a chemical reaction can often be determined by the properties of a rank-1 saddle and the associated transition state separating reactants and products. We have found evidence that such rates can be controlled and even enhanced by external driving in at least one such system. Specifically, we analyze a reactive model in two degrees of freedom that has been used earlier to describe driven chemical reactions. Therein, changes in the external driving can lead to a local maximum of the decay rate constant or even to bifurcations of periodic trajectories on the normally hyperbolic invariant manifold (NHIM) corresponding to the transition state. Inspired by these bifurcations, we show that in this case, the dynamics on the NHIM can be connected to the geometry of reactive trajectories and to reaction probabilities of Maxwell-Boltzmann distributed reactant ensembles.