The structure of symplectic integrators up to fourth order can be completely and analytically understood when the factorization (split) coefficients are related linearly but with a uniform nonlinear proportional factor. The analytic form of these extended-linear symplectic integrators greatly simplified proofs of their general properties and allowed easy construction of both forward and nonforward fourth-order algorithms with an arbitrary number of operators. Most fourth-order forward integrators can now be derived analytically from this extended-linear formulation without the use of symbolic algebra.
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http://dx.doi.org/10.1103/PhysRevE.73.026705 | DOI Listing |
Sci Rep
December 2024
Faculty of Physics and Applied Computer Science, AGH University of Krakow, al. Mickiewicza 30, 30-059, Kraków, Poland.
The concept of the symplectic covariance property of the Wigner distribution function and the symplectic invariance of the Wigner-Rényi entropies has been leveraged to estimate the interaction time of the moving quantum state in the presence of an absolutely integrable time-dependent potential. For this study, the considered scattering centre is represented initially by the Gaussian barrier. Two modifications of this potential energy are considered: a sudden change from barrier to barrier and from barrier to well.
View Article and Find Full Text PDFIEEE Trans Neural Netw Learn Syst
September 2024
Embedding the Hamiltonian formalisms into neural networks (NNs) enhances the reliability and precision of data-driven models, in which substantial research has been conducted. However, these approaches require the system to be represented in canonical coordinates, i.e.
View Article and Find Full Text PDFPhilos Trans A Math Phys Eng Sci
September 2024
Department DICCA, University of Genova, via Montallegro 1 , Genova, Italy.
This article focuses on characterizing a class of quasi-periodic metamaterials created through the repeated arrangement of an elementary cell in a fixed direction. The elementary cell consists of two building blocks made of elastic materials and arranged according to the generalized Fibonacci sequence, giving rise to a quasi-periodic finite microstructure, also called Fibonacci generation. By exploiting the transfer matrix method, the frequency band structure of selected periodic approximants associated with the Fibonacci superlattice, i.
View Article and Find Full Text PDFEntropy (Basel)
April 2024
Department of Chemistry, University of Crete, GR-700 13 Heraklion, Greece.
The common geometrical (symplectic) structures of classical mechanics, quantum mechanics, and classical thermodynamics are unveiled with three pictures. These cardinal theories, mainly at the non-relativistic approximation, are the cornerstones for studying chemical dynamics and chemical kinetics. Working in extended phase spaces, we show that the physical states of integrable dynamical systems are depicted by Lagrangian submanifolds embedded in phase space.
View Article and Find Full Text PDFChaos
March 2024
Center for Theoretical Physics of Complex Systems, Institute for Basic Science (IBS), Daejeon 34126, Republic of Korea.
We use the Toda chain model to demonstrate that numerical simulation of integrable Hamiltonian dynamics using time discretization destroys integrability and induces dynamical chaos. Specifically, we integrate this model with various symplectic integrators parametrized by the time step τ and measure the Lyapunov time TΛ (inverse of the largest Lyapunov exponent Λ). A key observation is that TΛ is finite whenever τ is finite but diverges when τ→0.
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