The phase space geometry underlying roaming reaction dynamics

Vladimír Krajňák*, Holger Waalkens

*Corresponding author for this work

Research output: Contribution to journalArticle (Academic Journal)peer-review

7 Citations (Scopus)
223 Downloads (Pure)

Abstract

Recent studies have found an unusual way of dissociation in formaldehyde. It can be characterized by a hydrogen atom that separates from the molecule, but instead of dissociating immediately it roams around the molecule for a considerable amount of time and extracts another hydrogen atom from the molecule prior to dissociation. This phenomenon has been coined roaming and has since been reported in the dissociation of a number of other molecules. In this paper we investigate roaming in Chesnavich’s (Formula presented.) model. During dissociation the free hydrogen must pass through three phase space bottleneck for the classical motion, that can be shown to exist due to unstable periodic orbits. None of these orbits is associated with saddle points of the potential energy surface and hence related to transition states in the usual sense. We explain how the intricate phase space geometry influences the shape and intersections of invariant manifolds that form separatrices, and establish the impact of these phase space structures on residence times and rotation numbers. Ultimately we use this knowledge to attribute the roaming phenomenon to particular heteroclinic intersections.
Original languageEnglish
Pages (from-to)2341-2378
Number of pages38
JournalJournal of Mathematical Chemistry
Volume56
Issue number8
Early online date8 Mar 2018
DOIs
Publication statusPublished - Sep 2018

Keywords

  • Reaction dynamics
  • Roaming
  • Transition state theory

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