Persistence of transition state structure in chemical reactions driven by fields oscillating in time

TL;DR

This paper develops a moving dividing surface in phase space that remains recrossing-free for time-dependent chemical reactions, extending transition state theory to dynamic barriers in both Hamiltonian and dissipative systems.

Contribution

It introduces a novel construction of a moving dividing surface that accurately captures transition states in reactions with time-varying barriers, applicable to complex anharmonic systems.

Findings

The moving dividing surface is recrossing-free in simulations.

Transition state theory applies to reactions with moving barriers.

Effective for both Hamiltonian and dissipative dynamics.

Abstract

Chemical reactions subjected to time-varying external forces cannot generally be described through a fixed bottleneck near the transition state barrier or dividing surface. A naive dividing surface attached to the instantaneous, but moving, barrier top also fails to be recrossing-free. We construct a moving dividing surface in phase space over a transition state trajectory. This surface is recrossing-free for both Hamiltonian and dissipative dynamics. This is confirmed even for strongly anharmonic barriers using simulation. The power of transition state theory is thereby applicable to chemical reactions and other activated processes even when the bottlenecks are time-dependent and move across space.