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When a chemical reaction is driven by an external field, the transition state that the system must pass through as it changes from reactant to product -for example, an energy barrier- becomes time-dependent. We show that for periodic…

Chemical Physics · Physics 2015-05-01 Galen T. Craven , Thomas Bartsch , Rigoberto Hernandez

Transition State Theory is a central cornerstone in reaction dynamics. Its key step is the identification of a dividing surface that is crossed only once by all reactive trajectories. This assumption is often badly violated, especially when…

Chemical Physics · Physics 2015-05-07 F. Revuelta , Thomas Bartsch , R. M. Benito , F. Borondo

Transition state theory formally provides a simplifying approach for determining chemical reaction rates and pathways. Given an underlying potential energy surface for a reactive system, one can determine the dividing surface in phase space…

Chemical reaction rates must increasingly be determined in systems that evolve under the control of external stimuli. In these systems, when a reactant population is induced to cross an energy barrier through forcing from a temporally…

Chemical Physics · Physics 2015-05-01 Galen T. Craven , Thomas Bartsch , Rigoberto Hernandez

Transition State Theory overestimates reaction rates in solution because conventional dividing surfaces between reagents and products are crossed many times by the same reactive trajectory. We describe a recipe for constructing a…

Statistical Mechanics · Physics 2007-05-23 Thomas Bartsch , Rigoberto Hernandez , T. Uzer

Classical transition state theory (TST) is the cornerstone of reaction rate theory. It postulates a partition of phase space into reactant and product regions, which are separated by a dividing surface that reactive trajectories must cross.…

Statistical Mechanics · Physics 2007-05-23 Thomas Bartsch , Rigoberto Hernandez , T. Uzer

Dynamics between reactants and products are often mediated by a rate-determining barrier and an associated dividing surface leading to the transition state theory rate. This framework is challenged when the barrier is time-dependent because…

Chemical Physics · Physics 2017-10-09 Matthias Feldmaier , Andrej Junginger , Jörg Main , Günter Wunner , Rigoberto Hernandez

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…

Chaotic Dynamics · Physics 2015-06-15 Ünver Çiftçi , Holger Waalkens

The accuracy of rate constants calculated using transition state theory depends crucially on the correct identification of a recrossing--free dividing surface. We show here that it is possible to define such optimal dividing surface in…

The fundamental assumption of conventional transition state theory is the existence of a dividing surface having the property that trajectories originating in reactants must cross the surface only once and then proceed to products. Recently…

Chaotic Dynamics · Physics 2007-05-23 H. Waalkens , S. Wiggins

A time-dependent no-recrossing dividing surface is shown to lead to a new criterion for identifying reactive trajectories well before they are evolved to infinite time. Numerical dynamics simulations of a dissipative anharmonic…

Statistical Mechanics · Physics 2009-11-11 Thomas Bartsch , T. Uzer , Jeremy M. Moix , Rigoberto Hernandez

A model is proposed for studying the reaction dynamics in complex quantum systems in which the complete mixing of states is hindered by an internal barrier. Such systems are often treated by the transition-state theory, also known in…

Quantum Physics · Physics 2021-11-03 G. F. Bertsch , K. Hagino

We examine the phase space structures that govern reaction dynamics in the absence of critical points on the potential energy surface. We show that in the vicinity of hyperbolic invariant tori it is possible to define phase space dividing…

The decay of quantum complex systems through a potential barrier is often described with transition-state theory, also known as RRKM theory in chemistry. Here we derive the basic formula for transition-state theory based on a generic…

Nuclear Theory · Physics 2024-04-02 K. Hagino , G. F. Bertsch

The crossing of a transition state in a multidimensional reactive system is mediated by invariant geometric objects in phase space: An invariant hyper-sphere that represents the transition state itself and invariant hyper-cylinders that…

Chaotic Dynamics · Physics 2013-04-29 Ali Allahem , Thomas Bartsch

The framework of transition state theory (TST) provides a powerful way for analyzing the dynamics of physical and chemical reactions. While TST has already been successfully used to obtain reaction rates for systems with a single…

Chemical Physics · Physics 2021-02-26 Johannes Reiff , Matthias Feldmaier , Jörg Main , Rigoberto Hernandez

The framework of transition state theory relies on the determination of a geometric structure identifying reactivity. It replaces the laborious exercise of following many trajectories for a long time to provide chemical reaction rates and…

Tunneling, though a physical reality, is shrouded in mystery. Wave packets cannot be constructed under the barrier and group velocity cannot be defined. The tunneling particle can be observed on either sides of the barrier but its…

Mesoscale and Nanoscale Physics · Physics 2023-03-01 Kanchan Meena , P. Singha Deo

In chemical or physical reaction dynamics, it is essential to distinguish precisely between reactants and products for all time. This task is especially demanding in time-dependent or driven systems because therein the dividing surface (DS)…

A sweep through a quantum phase transition by means of a time-dependent external parameter (e.g., pressure) entails non-equilibrium phenomena associated with a break-down of adiabaticity: At the critical point, the energy gap vanishes and…

Quantum Physics · Physics 2015-05-18 Ralf Schützhold
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