The Dynamical Matching Mechanism in Phase Space for Caldera-Type Potential Energy Surfaces

TL;DR

This paper investigates the phase space structures responsible for dynamical matching in caldera-type potential energy surfaces, revealing how heteroclinic trajectories influence trajectory trapping and the occurrence of dynamical matching.

Contribution

It provides a predictive understanding of dynamical matching by identifying heteroclinic trajectories as key phase space structures in caldera PES.

Findings

Heteroclinic trajectories cause trapping in the caldera region.

Breaking heteroclinic trajectories leads to dynamical matching.

Parameter variations can control the occurrence of dynamical matching.

Abstract

Dynamical matching occurs in a variety of important organic chemical reactions. It is observed to be a result of a potential energy surface (PES) having specific geometric features. In particular, a region of relative flatness where entrance and exit to this region is controlled by index-one saddles. Examples of potential energy surfaces having these features are the so-called caldera potential energy surfaces. We develop a predictive level of understanding of the phenomenon of dynamical matching in a caldera potential energy surface. We show that the phase space structure that governs dynamical matching is a particular type of heteroclinic trajectory which gives rise to trapping of trajectories in the central region of the caldera PES. When the heteroclinic trajectory is broken, as a result of parameter variations, then dynamical matching occurs.