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The quantum normal form approach to quantum transition state theory is used to compute the cumulative reaction probability for collinear exchange reactions. It is shown that for heavy atom systems like the nitrogen exchange reaction the…

Chemical Physics · Physics 2010-03-17 Arseni Goussev , Roman Schubert , Holger Waalkens , Stephen Wiggins

A quantum version of transition state theory based on a quantum normal form (QNF) expansion about a saddle-centre-...-centre equilibrium point is presented. A general algorithm is provided which allows one to explictly compute QNF to any…

Chaotic Dynamics · Physics 2007-12-12 Holger Waalkens , Roman Schubert , Stephen Wiggins

Studying chemical reactions, particularly in the gas phase, relies heavily on computing scattering matrix elements. These elements are essential for characterizing molecular reactions and accurately determining reaction probabilities.…

Quantum Physics · Physics 2024-04-24 Sumit Suresh Kale , Sabre Kais

Transition State Theory forms the basis of computing reaction rates in chemical and other systems. Recently it has been shown how transition state theory can rigorously be realized in phase space using an explicit algorithm. The…

Chaotic Dynamics · Physics 2010-07-27 Roman Schubert , Holger Waalkens , Arseni Goussev , Stephen Wiggins

In this work we provide a complete model of semiclassical theories by including back-reaction and correlation into the picture. We specially aim at the interaction between light and a two-level atom, and we also illustrate it via the…

Quantum Physics · Physics 2019-10-28 Gerardo García , Laura Ares , Alfredo Luis

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

We extend the Wigner-Weyl-Moyal phase-space formulation of quantum mechanics to general curved configuration spaces. The underlying phase space is based on the chosen coordinates of the manifold and their canonically conjugate momenta. The…

Quantum Physics · Physics 2023-02-07 Clemens Gneiting , Timo Fischer , Klaus Hornberger

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 new approach is described to the evaluation of the S-matrix in three-dimensional atom-diatom reactive quantum scattering theory. The theory is developed based on natural collision coordinates where progress along the reaction coordinate…

Chemical Physics · Physics 2007-05-23 Ashot S. Gevorkyan , Gabriel G. Balint-Kurti , Gunnar Nyman

We describe a method for obtaining the scattering matrix for nuclear or chemical reactions on a finite lattice. Aside from the preparation of the initial and final states as wave packets, the only other operation required is unitary time…

Nuclear Theory · Physics 2026-03-31 Evan Rule , Ionel Stetcu

We propose a hybrid quantum-classical framework to solve the elastic scattering phase shift of two well-bound nuclei in an uncoupled channel. Within this framework, we develop a many-body formalism in which the continuum scattering states…

Nuclear Theory · Physics 2024-08-14 Peiyan Wang , Weijie Du , Wei Zuo , James P. Vary

Time-symmetric quantum mechanics can be described in the usual Weyl--Wigner--Moyal formalism (WWM) by using the properties of the Wigner distribution, and its generalization, the cross-Wigner distribution. The use of the latter makes clear…

Quantum Physics · Physics 2015-10-12 Charlyne de Gosson , Maurice de Gosson

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 develop a statistical theory that describes quantum-mechanical scattering of a particle by a cavity when the geometry is such that the classical dynamics is chaotic. This picture is relevant to a variety of physical systems, ranging from…

Mesoscale and Nanoscale Physics · Physics 2016-12-21 Pier A. Mello , Victor A. Gopar , J. A. Mendez-Bermudez

In physics, one is often misled in thinking that the mathematical model of a system is part of or is that system itself. Think of expressions commonly used in physics like "point" particle, motion "on the line", "smooth" observables, wave…

Quantum Physics · Physics 2019-11-06 Jean-Pierre Gazeau

In this paper, we address the phase space formulation of the Jaynes-Cummings model through the explicit construction of the full Wigner function for a hybrid bipartite quantum system composed of a two-level atom and a quantized coherent…

Quantum Physics · Physics 2025-07-01 Mar Sanchez-Cordova , Jasel Berra-Montiel , Alberto Molgado

Quantum tomography has become an indispensable tool in order to compute the density matrix $\rho$ of quantum systems in Physics. Recently, it has further gained importance as a basic step to test entanglement and violation of Bell…

High Energy Physics - Phenomenology · Physics 2024-10-04 Alexander Bernal

Wigner's quasi-probability distribution function in phase-space is a special (Weyl) representation of the density matrix. It has been useful in describing quantum transport in quantum optics; nuclear physics; decoherence (eg, quantum…

High Energy Physics - Theory · Physics 2008-11-26 Cosmas K Zachos

For triatomic chemical reactions under single-collision conditions, we propose a new quasi-classical trajectory (QCT) approach to rotational-state distributions of particular interest in the quantum regime where only a few rotational states…

Chemical Physics · Physics 2014-05-02 L. Bonnet , P. Larrégaray , Ph. Halvick , J. -C. Rayez

On the basis of a coherent state representation of quantum noise operator and an ensemble averaging procedure a scheme for quantum Brownian motion has been proposed recently [Banerjee {\it et al}, Phys. Rev. E {\bf65}, 021109 (2002);…

Statistical Mechanics · Physics 2009-11-10 Debashis Barik , Suman Kumar Banik , Deb Shankar Ray
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