title: Nonstatistical dynamics on the caldera.
abstract: We explore both classical and quantum dynamics of a model potential exhibiting a caldera: that is, a shallow potential well with two pairs of symmetry related index one saddles associated with entrance/exit channels. Classical trajectory simulations at several different energies confirm the existence of the "dynamical matching" phenomenon originally proposed by Carpenter, where the momentum direction associated with an incoming trajectory initiated at a high energy saddle point determines to a considerable extent the outcome of the reaction (passage through the diametrically opposing exit channel). By studying a "stretched" version of the caldera model, we have uncovered a generalized dynamical matching: bundles of trajectories can reflect off a hard potential wall so as to end up exiting predominantly through the transition state opposite the reflection point. We also investigate the effects of dissipation on the classical dynamics. In addition to classical trajectory studies, we examine the dynamics of quantum wave packets on the caldera potential (stretched and unstretched). These computations reveal a quantum mechanical analogue of the "dynamical matching" phenomenon, where the initial expectation value of the momentum direction for the wave packet determines the exit channel through which most of the probability density passes to product.
authors: School of Mathematics, University of Bristol, Bristol BS8 1TW, United Kingdom.
authors: Peter
authors: P
authors: Collins
authors: Department of Chemistry and Chemical Biology, Baker Laboratory, Cornell University, Ithaca, New York 14853, USA.
authors: Zeb C
authors: ZC
authors: Kramer
authors: School of Chemistry, Cardiff University, Cardiff CF10 3AT, United Kingdom.
authors: Barry K
authors: BK
authors: Carpenter
authors: Department of Chemistry and Chemical Biology, Baker Laboratory, Cornell University, Ithaca, New York 14853, USA.
authors: Gregory S
authors: GS
authors: Ezra
authors: School of Mathematics, University of Bristol, Bristol BS8 1TW, United Kingdom.
authors: Stephen
authors: S
authors: Wiggins