We provide a dynamical interpretation of the recently identified `roaming' mechanism for molecular dissociation reactions in terms of geometrical structures in phase space. These are NHIMs (Normally Hyperbolic Invariant Manifolds) and their stable/unstable manifolds that define transition states for ion-molecule association or dissociation reactions. The associated dividing surfaces rigorously define a roaming region of phase space, in which both reactive and nonreactive trajectories can be trapped for arbitrarily long times.
@article{arxiv.1309.6432,
title = {Multiple Transition States and Roaming in Ion-Molecule Reactions: a Phase Space Perspective},
author = {Frederic A. L. Mauguiere and Peter Collins and Gregory S. Ezra and Stavros C. Farantos and Stephen Wiggins},
journal= {arXiv preprint arXiv:1309.6432},
year = {2015}
}