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Anomalous Diffusion with an Apparently Negative Diffusion Coefficient in a One-Dimensional Quantum Molecular Chain Model. Symmetry (Basel) 2021. [DOI: 10.3390/sym13030506] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Abstract
An interesting anomaly in the diffusion process with an apparently negative diffusion coefficient defined through the mean-square displacement in a one-dimensional quantum molecular chain model is shown. Nevertheless, the system satisfies the H-theorem so that the second law of thermodynamics is satisfied. The reason why the “diffusion constant” becomes negative is due to the effect of the phase mixing process, which is a characteristic result of the one-dimensionality of the system. We illustrate the situation where this negative “diffusion constant” appears.
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Nakade S, Kanki K, Tanaka S, Petrosky T. Anomalous diffusion of a quantum Brownian particle in a one-dimensional molecular chain. Phys Rev E 2020; 102:032137. [PMID: 33075955 DOI: 10.1103/physreve.102.032137] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2020] [Accepted: 08/25/2020] [Indexed: 11/07/2022]
Abstract
We discuss anomalous relaxation processes of a quantum Brownian particle which interacts with an acoustic phonon field as a thermal reservoir in one-dimensional chain molecule. We derive a kinetic equation for the particle using the complex spectral representation of the Liouville-von Neumann operator. Due to the one-dimensionality, the momentum space separates into infinite sets of disjoint irreducible subspaces dynamically independent of one another. Hence, momentum relaxation occurs only within each subspace toward the Maxwell distribution. We obtain a hydrodynamic mode with transport coefficients, a sound velocity, and a diffusion coefficient, defined in each subspace. Moreover, because the sound velocity has momentum dependence, phase mixing affects the broadening of the spatial distribution of the particle in addition to the diffusion process. Due to the phase mixing, the increase rate of the mean-square displacement of the particle increases linearly with time and diverges in the long-time limit.
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Affiliation(s)
- Sho Nakade
- Department of Physical Science, Osaka Prefecture University, Sakai, Osaka 599-8531, Japan
| | - Kazuki Kanki
- Department of Physical Science, Osaka Prefecture University, Sakai, Osaka 599-8531, Japan
| | - Satoshi Tanaka
- Department of Physical Science, Osaka Prefecture University, Sakai, Osaka 599-8531, Japan
| | - Tomio Petrosky
- Center for Complex Quantum Systems, The University of Texas at Austin, Austin, Texas 78712, USA.,Institute of Industrial Science, The University of Tokyo, Tokyo 153-8505, Japan
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Kuzkin VA, Liazhkov SD. Equilibration of kinetic temperatures in face-centered cubic lattices. Phys Rev E 2020; 102:042219. [PMID: 33212745 DOI: 10.1103/physreve.102.042219] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2020] [Accepted: 10/02/2020] [Indexed: 11/07/2022]
Abstract
We study thermal equilibration in face-centered cubic lattices with harmonic and anharmonic (Lennard-Jones) interactions. Initial conditions are chosen such that the kinetic temperatures, corresponding to three spatial directions, are different. We show that in the anharmonic case the approach to thermal equilibrium has two time scales. The first time scale is the period of atomic vibration. At times of the order of several atomic periods, the approach to equilibrium is accompanied by decaying high frequency oscillations of the temperatures. The oscillations are described analytically using the harmonic approximation. In particular, the characteristic frequencies of the oscillations are calculated. It is shown that the oscillations decay in time more slowly than expected. The second time scale, presented in the anharmonic case only, depends on the initial temperature of the system. Normalizing time by this scale, we obtain numerically a universal curve describing equilibration in the Lennard-Jones crystal over a wide range of temperatures.
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Affiliation(s)
- Vitaly A Kuzkin
- Peter the Great Saint Petersburg Polytechnical University, Saint Petersburg, Russia.,Institute for Problems in Mechanical Engineering RAS, Saint Petersburg, Russia
| | - Sergei D Liazhkov
- Peter the Great Saint Petersburg Polytechnical University, Saint Petersburg, Russia
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Berinskii I, Kuzkin VA. Equilibration of energies in a two-dimensional harmonic graphene lattice. PHILOSOPHICAL TRANSACTIONS. SERIES A, MATHEMATICAL, PHYSICAL, AND ENGINEERING SCIENCES 2020; 378:20190114. [PMID: 31760904 PMCID: PMC6894525 DOI: 10.1098/rsta.2019.0114] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Accepted: 07/09/2019] [Indexed: 06/10/2023]
Abstract
We study dynamical phenomena in a harmonic graphene (honeycomb) lattice, consisting of equal particles connected by linear and angular springs. Equations of in-plane motion for the lattice are derived. Initial conditions typical for molecular dynamic modelling are considered. Particles have random initial velocities and zero displacements. In this case, the lattice is far from thermal equilibrium. In particular, initial kinetic and potential energies are not equal. Moreover, initial kinetic energies (and temperatures), corresponding to degrees of freedom of the unit cell, are generally different. The motion of particles leads to equilibration of kinetic and potential energies and redistribution of kinetic energy among degrees of freedom. During equilibration, the kinetic energy performs decaying high-frequency oscillations. We show that these oscillations are accurately described by an integral depending on dispersion relation and polarization matrix of the lattice. At large times, kinetic and potential energies tend to equal values. Kinetic energy is partially redistributed among degrees of freedom of the unit cell. Equilibrium distribution of the kinetic energies is accurately predicted by the non-equipartition theorem. Presented results may serve for better understanding of the approach to thermal equilibrium in graphene. This article is part of the theme issue 'Modelling of dynamic phenomena and localization in structured media (part 2)'.
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Affiliation(s)
- I. Berinskii
- School of Mechanical Engineering, Tel Aviv University, Tel Aviv, Israel
| | - V. A. Kuzkin
- Higher School of Theoretical Mechanics, Peter the Great St Petersburg Polytechnical University, Sankt-Peterburg, Russian Federation
- Institute for Problems in Mechanical Engineering RAS, Sankt Peterburg, Russian Federation
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Gavrilov SN, Krivtsov AM. Thermal equilibration in a one-dimensional damped harmonic crystal. Phys Rev E 2019; 100:022117. [PMID: 31574650 DOI: 10.1103/physreve.100.022117] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2019] [Indexed: 11/07/2022]
Abstract
The features for the unsteady process of thermal equilibration ("the fast motions") in a one-dimensional harmonic crystal lying in a viscous environment (e.g., a gas) are under investigation. It is assumed that initially the displacements of all the particles are zero and the particle velocities are random quantities with zero mean and a constant variance, thus, the system is far away from the thermal equilibrium. It is known that in the framework of the corresponding conservative problem the kinetic and potential energies oscillate and approach the equilibrium value that equals a half of the initial value of the kinetic energy. We show that the presence of the external damping qualitatively changes the features of this process. The unsteady process generally has two stages. At the first stage oscillations of kinetic and potential energies with decreasing amplitude, subjected to exponential decay, can be observed (this stage exists only in the underdamped case). At the second stage (which always exists), the oscillations vanish, and the energies are subjected to a power decay. The large- time asymptotics for the energy is proportional to t^{-3/2} in the case of the potential energy and to t^{-5/2} in the case the kinetic energy. Hence, at large values of time the total energy of the crystal is mostly the potential energy. The obtained analytic results are verified by independent numerical calculations.
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Affiliation(s)
- S N Gavrilov
- Institute for Problems in Mechanical Engineering RAS, V.O., Bolshoy pr. 61, St. Petersburg 199178, Russia and Peter the Great St. Petersburg Polytechnic University (SPbPU), Polytechnicheskaya str. 29, St.Petersburg 195251, Russia
| | - A M Krivtsov
- Institute for Problems in Mechanical Engineering RAS, V.O., Bolshoy pr. 61, St. Petersburg 199178, Russia and Peter the Great St. Petersburg Polytechnic University (SPbPU), Polytechnicheskaya str. 29, St.Petersburg 195251, Russia
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Murachev AS, Krivtsov AM, Tsvetkov DV. Thermal echo in a finite one-dimensional harmonic crystal. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2019; 31:095702. [PMID: 30523871 DOI: 10.1088/1361-648x/aaf3c6] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
An instant homogeneous thermal perturbation in the finite harmonic one-dimensional crystal is studied. Previously it was shown that for the same problem in the infinite crystal the kinetic temperature oscillates with decreasing amplitude described by the Bessel function of the first kind. In the present paper it is shown that in the finite crystal this behavior is observed only until a certain period of time when a sharp increase of the oscillation amplitude is realized. This phenomenon, further referred to as the thermal echo, occurs periodically, with the period proportional to the crystal length. The amplitude for each subsequent echo is lower than for the previous one. It is obtained analytically that the time-dependence of the kinetic temperature can be described by an infinite sum of the Bessel functions with multiple indices. It is also shown that the thermal echo in the thermodynamic limit is described by the Airy function.
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Affiliation(s)
- A S Murachev
- Peter the Great Saint Petersburg Polytechnic University, Saint Petersburg, Russia
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Usha Devi AR, Rajagopal AK. Dynamical evolution of quantum oscillators toward equilibrium. PHYSICAL REVIEW. E, STATISTICAL, NONLINEAR, AND SOFT MATTER PHYSICS 2009; 80:011136. [PMID: 19658682 DOI: 10.1103/physreve.80.011136] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/11/2009] [Revised: 07/02/2009] [Indexed: 05/28/2023]
Abstract
A pure quantum state of large number N of oscillators, interacting via harmonic coupling, evolves such that any small subsystem n<<N of the global state approaches equilibrium. This provides a different example where stability emerges as natural phenomena under quantum dynamics alone, with no necessity to bring in any additional statistical postulates. Mixing of equilibrated subsystems consisting of 1,2,...,n<<N clearly indicates that small subsystems are entangled with the rest of the state, i.e., the bath. Every single mode oscillator is found to relax in a mixed density matrix of the Boltzmann canonical form. In two oscillator stationary subsystems, intraentanglement within the "system" oscillators is found to exist when the magnitude of the squeezing parameter of the bath is comparable in magnitude with that of the coupling strength.
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Affiliation(s)
- A R Usha Devi
- Department of Physics, Bangalore University, Bangalore 560 056, India.
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Petrosky T, Ting CO, Garmon S. Strongly coupled matter field and nonanalytic decay rate of dipole molecules in a waveguide. PHYSICAL REVIEW LETTERS 2005; 94:043601. [PMID: 15783556 DOI: 10.1103/physrevlett.94.043601] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/13/2004] [Indexed: 05/24/2023]
Abstract
The decay rate gamma of an excited dipole molecule inside a waveguide is evaluated for the strongly coupled matter-field case near a cutoff frequency omegac without using perturbation analysis. Because of the singularity in the density of photon states at the cutoff frequency, we find that gamma depends nonanalytically on the coupling constant g as g4/3, which leads to a vast increase in the decay rate.
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Affiliation(s)
- T Petrosky
- Center for Studies in Statistical Mechanics and Complex Systems, The University of Texas at Austin, Austin, Texas 78712 USA.
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Mareschal M, Amellal A. Thermal conductivity in a one-dimensional Lennard-Jones chain by molecular dynamics. PHYSICAL REVIEW. A, GENERAL PHYSICS 1988; 37:2189-2196. [PMID: 9899914 DOI: 10.1103/physreva.37.2189] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
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Cukier R, Mazur P. The ergodic properties of an impurity in a harmonic oscillator chain. ACTA ACUST UNITED AC 1971. [DOI: 10.1016/0031-8914(71)90068-1] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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Oppenheim I, Shuler KE, Weiss GH. Decay of Correlations. II. Relaxation of Momentum Correlations and Momentum Distributions in Harmonic Oscillator Chains. J Chem Phys 1969. [DOI: 10.1063/1.1671610] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
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Allen KR, Ford J. Lattice Thermal Conductivity for a One-Dimensional, Harmonic, Isotopically Disordered Crystal. ACTA ACUST UNITED AC 1968. [DOI: 10.1103/physrev.176.1046] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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Rubin RJ. Momentum Autocorrelation Functions and Energy Transport in Harmonic Crystals Containing Isotopic Defects. ACTA ACUST UNITED AC 1963. [DOI: 10.1103/physrev.131.964] [Citation(s) in RCA: 76] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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Schmidt E. Fortschritte der Verfahrenstechnik. Thermodynamik. CHEM-ING-TECH 1957. [DOI: 10.1002/cite.330290203] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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Statistical mechanics of irreversible processes Part VIII: general theory of weakly coupled systems. ACTA ACUST UNITED AC 1956. [DOI: 10.1016/s0031-8914(56)90009-x] [Citation(s) in RCA: 111] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
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Van Hove L. Correlations in Space and Time and Born Approximation Scattering in Systems of Interacting Particles. ACTA ACUST UNITED AC 1954. [DOI: 10.1103/physrev.95.249] [Citation(s) in RCA: 2306] [Impact Index Per Article: 32.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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