Reaction dynamics through kinetic transition states

TL;DR

This paper introduces the concept of kinetic transition states as a new type of bottleneck in phase space that mediates kinetic changes, demonstrated through the rotational vibrational motion of a triatomic molecule.

Contribution

It presents the theoretical framework for kinetic transition states, expanding the understanding of phase space bottlenecks beyond configurational changes.

Findings

Identification of phase space structures related to kinetic transition states

Analysis of their dynamical implications for molecular motion

Extension of phase space concepts to broader dynamical systems

Abstract

The transformation of a system from one state to another is often mediated by a bottleneck in the system's phase space. In chemistry these bottlenecks are known as \emph{transition states} through which the system has to pass in order to evolve from reactants to products. The chemical reactions are usually associated with configurational changes where the reactants and products states correspond, e.g., to two different isomers or the undissociated and dissociated state of a molecule or cluster. In this letter we report on a new type of bottleneck which mediates \emph{kinetic} rather than configurational changes. The phase space structures associated with such \emph{kinetic transition states} and their dynamical implications are discussed for the rotational vibrational motion of a triatomic molecule. An outline of more general related phase space structures with important dynamical implications is given.