Thermalization of oscillator chains with onsite anharmonicity and comparison with kinetic theory

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Mendl , C B , Lu , J & Lukkarinen , J 2016 , ' Thermalization of oscillator chains with onsite anharmonicity and comparison with kinetic theory ' , Physical Review E : Statistical, Nonlinear, and Soft Matter Physics , vol. 94 , no. 6 , 062104 . https://doi.org/10.1103/PhysRevE.94.062104

Title: Thermalization of oscillator chains with onsite anharmonicity and comparison with kinetic theory
Author: Mendl, Christian B.; Lu, Jianfeng; Lukkarinen, Jani
Contributor: University of Helsinki, Department of Mathematics and Statistics
Date: 2016-12-02
Language: eng
Number of pages: 9
Belongs to series: Physical Review E : Statistical, Nonlinear, and Soft Matter Physics
ISSN: 1539-3755
URI: http://hdl.handle.net/10138/178037
Abstract: We perform microscopic molecular dynamics simulations of particle chains with an onsite anharmonicity to study relaxation of spatially homogeneous states to equilibrium, and directly compare the simulations with the corresponding Boltzmann-Peierls kinetic theory. The Wigner function serves as a common interface between the microscopic and kinetic level. We demonstrate quantitative agreement after an initial transient time interval. In particular, besides energy conservation, we observe the additional quasiconservation of the phonon density, defined via an ensemble average of the related microscopic field variables and exactly conserved by the kinetic equations. On superkinetic time scales, density quasiconservation is lost while energy remains conserved, and we find evidence for eventual relaxation of the density to its canonical ensemble value. However, the precise mechanism remains unknown and is not captured by the Boltzmann-Peierls equations.
Subject: PHONON BOLTZMANN-EQUATION
ENERGY-TRANSPORT
CONDUCTIVITY
DYNAMICS
114 Physical sciences
111 Mathematics
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