Langevin Dynamics with Spatial Correlations as a Model for Electron-Phonon Coupling
[4];
- Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States). Quantum Simulations Group
- Virginia Polytechnic Inst. and State Univ. (Virginia Tech), Arlington, VA (United States). Dept. of Mechanical Engineering
- George Washington Univ., Ashburn, VA (United States)
- Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). Materials Science and Technology Division
- Uppsala Univ. (Sweden). Dept. of Physics and Astronomy
Stochastic Langevin dynamics has been traditionally used as a tool to describe nonequilibrium processes. When utilized in systems with collective modes, traditional Langevin dynamics relaxes all modes indiscriminately, regardless of their wavelength. In this paper, we propose a generalization of Langevin dynamics that can capture a differential coupling between collective modes and the bath, by introducing spatial correlations in the random forces. This allows modeling the electronic subsystem in a metal as a generalized Langevin bath endowed with a concept of locality, greatly improving the capabilities of the two-temperature model. The specific form proposed here for the spatial correlations produces a physical wave-vector and polarization dependency of the relaxation produced by the electron-phonon coupling in a solid. We show that the resulting model can be used for describing the path to equilibration of ions and electrons and also as a thermostat to sample the equilibrium canonical ensemble. By extension, the family of models presented here can be applied in general to any dense system, solids, alloys, and dense plasmas. Finally, as an example, we apply the model to study the nonequilibrium dynamics of an electron-ion two-temperature Ni crystal.
- Research Organization:
- Energy Frontier Research Centers (EFRC) (United States). Energy Dissipation to Defect Evolution (EDDE); Lawrence Livermore National Laboratory (LLNL), Livermore, CA (United States); Oak Ridge National Laboratory (ORNL), Oak Ridge, TN (United States)
- Sponsoring Organization:
- USDOE Office of Science (SC), Basic Energy Sciences (BES)
- Grant/Contract Number:
- AC52-07NA27344; AC05-00OR22725
- OSTI ID:
- 1458684
- Alternate ID(s):
- OSTI ID: 1436003; OSTI ID: 1459271
- Report Number(s):
- LLNL-JRNL-743460; 898486; TRN: US1901505
- Journal Information:
- Physical Review Letters, Vol. 120, Issue 18; ISSN 0031-9007
- Publisher:
- American Physical Society (APS)Copyright Statement
- Country of Publication:
- United States
- Language:
- English
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