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We study the effect of changes in the parameters of a two-dimensional potential energy surface on the phase space structures relevant for chemical reaction dynamics. The changes in the potential energy are representative of chemical…

Dynamical Systems · Mathematics 2021-07-28 Wenyang Lyu , Shibabrat Naik , Stephen Wiggins

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

We present a method that generalizes the periodic orbit dividing surface construction for Hamiltonian systems with three or more degrees of freedom. We construct a torus using as a basis a periodic orbit and we extend this to a $2n-2$…

Chaotic Dynamics · Physics 2021-08-25 M. Katsanikas , S. Wiggins

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

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

In this paper we unveil the geometrical template of phase space structures that governs transport in a Hamiltonian system described by a potential energy surface with an entrance/exit channel and two wells separated by an index-1 saddle.…

Chaotic Dynamics · Physics 2020-07-29 M. Katsanikas , V. J. García-Garrido , M. Agaoglou , S. Wiggins

Recently the phase space structures governing reaction dynamics in Hamiltonian systems have been identified and algorithms for their explicit construction have been developed. These phase space structures are induced by saddle type…

Chaotic Dynamics · Physics 2015-05-28 Unver Ciftci , Holger Waalkens

We study the orbital behavior at the neighborhood of complex unstable periodic orbits in a 3D autonomous Hamiltonian system of galactic type. At a transition of a family of periodic orbits from stability to complex instability (also known…

Chaotic Dynamics · Physics 2017-01-09 M. Katsanikas , P. A. Patsis , G. Contopoulos

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

In a 2D conservative Hamiltonian system there is a formal integral $\Phi$ besides the energy H. This is not convergent near a stable periodic orbit, but it is convergent near an unstable periodic orbit. We explain this difference and we…

Chaotic Dynamics · Physics 2014-10-13 G. Contopoulos , C. Efthymiopoulos , M. Katsanikas

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

We develop the geometrical, analytical, and computational framework for reactive island theory for three degrees-of-freedom time-independent Hamiltonian systems. In this setting, the dynamics occurs in a 5-dimensional energy surface in…

Chaotic Dynamics · Physics 2021-07-14 Vladimír Krajňák , Víctor J. García-Garrido , Stephen Wiggins

We establish a hierarchical ordering of periodic orbits in a strongly coupled multidimensional Hamiltonian system. Phase space structures can be reconstructed quantitatively from the knowledge of periodic orbits alone. We illustrate our…

Chaotic Dynamics · Physics 2007-05-23 S. Gekle , J. Main , T. Bartsch , T. Uzer

It has been recently argued that near-integrable nonautonomous one-degree-of-freedom Hamiltonian systems are constrained by KAM theory even when the time-dependent (nonintegrable) part of the Hamiltonian is given in the form of a…

Chaotic Dynamics · Physics 2007-05-23 F. J. Beron-Vera , M. J. Olascoaga , M. G. Brown

We implement the geometric method proposed in ([9], [3], [16]) to analytically predict the sequence of bifurcations leading to a change of stability and/or the appearance of new periodic orbits in the secular 3D planetary three body…

Mathematical Physics · Physics 2025-10-01 Rita Mastroianni , Antonella Marchesiello , Christos Efthymiopoulos , Giuseppe Pucacco

In this paper, we study the quantum dynamics of a one degree-of-freedom (DOF) Hamiltonian that is a normal form for a saddle node bifurcation of equilibrium points in phase space. The Hamiltonian has the form of the sum of kinetic energy…

Quantum Physics · Physics 2021-07-05 Wenyang Lyu , Shibabrat Naik , Stephen Wiggins

We propose and study a model for the equilibrium statistical mechanics of a pressurised semiflexible polymer ring. The Hamiltonian has a term which couples to the algebraic area of the ring and a term which accounts for bending…

Statistical Mechanics · Physics 2009-11-13 Mithun K. Mitra , Gautam I. Menon , R. Rajesh

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…

We investigate the relation between the phase space structure of Hamiltonian and non-Hamiltonian deterministic thermostats. We show that phase space structures governing reaction dynamics in Hamiltonian systems map to the same type of phase…

Statistical Mechanics · Physics 2008-10-21 Gregory S. Ezra , Stephen Wiggins

Chemical selectivity is a phenomenon displayed by potential energy surfaces (PES) that is relevant for many organic chemical reactions whose PES feature a valley-ridge inflection point (VRI) in the region between two sequential index-1…

Chemical Physics · Physics 2020-07-15 M. Agaoglou , V. J. Garcıa-Garrido , M. Katsanikas , S. Wiggins
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