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In chemical reactions, trajectories typically turn from reactants to products when crossing a dividing surface close to the normally hyperbolic invariant manifold (NHIM) given by the intersection of the stable and unstable manifolds of a…

Chemical Physics · Physics 2020-11-10 Manuel Kuchelmeister , Johannes Reiff , Jörg Main , Rigoberto Hernandez

Reaction rates of chemical reactions under nonequilibrium conditions can be determined through the construction of the normally hyperbolic invariant manifold (NHIM) [and moving dividing surface (DS)] associated with the transition state…

Chemical reactions in multidimensional systems are often described by a rank-1 saddle, whose stable and unstable manifolds intersect in the normally hyperbolic invariant manifold (NHIM). Trajectories started on the NHIM in principle never…

Chemical Physics · Physics 2020-02-25 Martin Tschöpe , Matthias Feldmaier , Jörg Main , Rigoberto Hernandez

Recent work has shown that in a non-thermal, multidimensional system, the trajectories in the activated complex possess different instantaneous and time-averaged reactant decay rates. Under dissipative dynamics, it is known that these…

Chemical Physics · Physics 2021-01-06 Robin Bardakcioglu , 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…

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

Chemical reactions in multidimensional driven systems are typically described by a time-dependent rank-1 saddle associated with one reaction and several orthogonal coordinates (including the solvent bath). To investigate reactions in such…

Chemical Physics · Physics 2020-02-06 Matthias Feldmaier , Robin Bardakcioglu , Johannes Reiff , Jörg Main , Rigoberto Hernandez

A model Hamiltonian for the reaction CH$_4^+ \rightarrow$ CH$_3^+$ + H, parametrized to exhibit either early or late inner transition states, is employed to investigate the dynamical characteristics of the roaming mechanism. Tight/loose…

Chemical Physics · Physics 2015-06-18 F. A. L. Mauguière , P. Collins , G. S. Ezra , S. C. Farantos , S. Wiggins

External flows of energy, entropy, and matter can cause sudden transitions in the stability of biological and industrial systems, fundamentally altering their dynamical function. How might we control and design these transitions in chemical…

Molecular Networks · Quantitative Biology 2023-06-19 Zachary G. Nicolaou , Schuyler B. Nicholson , Adilson E. Motter , Jason R. Green

Hamiltonian dynamical systems possessing equilibria of ${saddle} \times {centre} \times...\times {centre}$ stability type display \emph{reaction-type dynamics} for energies close to the energy of such equilibria; entrance and exit from…

Chaotic Dynamics · Physics 2015-05-13 Holger Waalkens , Stephen Wiggins

Many biological molecular motors and machines are driven by chemical reactions that occur in specific catalytic sites. We study whether the arrival of molecules to such an active site can be accelerated by the presence of a nearby inactive…

Statistical Mechanics · Physics 2025-01-06 Hila Katznelson , Saar Rahav

We consider the existence of invariant manifolds in phase space governing reaction dynamics in situations where there are no saddle points on the potential energy surface in the relevant regions of configuration space. We point out that…

Chemical Physics · Physics 2010-11-04 Gregory S. Ezra , Stephen Wiggins

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

We study the phase space geometry associated with index 2 saddles of a potential energy surface and its influence on reaction dynamics for $n$ degree-of-freedom (DoF) Hamiltonian systems. For index 1 saddles of potential energy surfaces…

Chaotic Dynamics · Physics 2015-05-13 Gregory S. Ezra , Stephen Wiggins

Chemical reactions involve the movement of charges, and this work presents a mathematical model for describing chemical reactions in electrolytes. The model is developed using an energy variational method that aligns with classical…

Chemical Physics · Physics 2023-11-02 Shixin Xu , Robert Eisenberg , Zilong Song , Huaxiong Huang

In this article we present the influence of a Hamiltonian saddle-node bifurcation on the high-dimensional phase space structures that mediate reaction dynamics. To achieve this goal, we identify the phase space invariant manifolds using…

Chaotic Dynamics · Physics 2020-05-20 Víctor J. García-Garrido , Shibabrat Naik , Stephen Wiggins

Reactivity boundaries that divide the destination and the origin of trajectories are of crucial importance to reveal the mechanism of reactions. We investigate whether such reactivity boundaries can be extracted for higher index saddles in…

Chemical Physics · Physics 2013-06-27 Yutaka Nagahata , Hiroshi Teramoto , Chun-Biu Li , Shinnosuke Kawai , Tamiki Komatsuzaki

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…

Classical theories of chemical kinetics assume independent reactions in dilute solutions, whose rates are determined by mean concentrations. In condensed matter, strong interactions alter chemical activities and create inhomogeneities that…

Materials Science · Physics 2013-04-17 Martin Z. Bazant

Phase space structures such as dividing surfaces, normally hyperbolic invariant manifolds, their stable and unstable manifolds have been an integral part of computing quantitative results such as transition fraction, stability erosion in…

Dynamical Systems · Mathematics 2019-07-09 Shibabrat Naik , Víctor J. García-Garrido , Stephen Wiggins
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