Thermostat-induced spurious interfacial resistance in non-equilibrium molecular dynamics simulations of solid-liquid and solid-solid systems

Ghatage, D and Tomar, G and Shukla, RK (2020) Thermostat-induced spurious interfacial resistance in non-equilibrium molecular dynamics simulations of solid-liquid and solid-solid systems. In: Journal of Chemical Physics, 153 (16).

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Abstract

Non-equilibrium molecular dynamics (NEMD) simulations universally rely on thermostats to control temperature. The thermostat-induced alteration in the system dynamics that enables temperature control can, however, adversely impact molecular transport across the temperature-controlled and temperature-uncontrolled regions. Here, we analyze the influence of a thermostat on thermal transport across a solid-liquid interface in a canonical setup that, owing to its generality, has been widely employed in NEMD simulations. In scenarios wherein temperature is controlled via stochastic/frictional forcing based thermostats, we find occurrence of a spurious temperature jump across the solid-liquid interface. The corresponding Kapitza length diminishes with a gradual weakening of the coupling between the thermostat and the system. Hence, we identify an optimal thermostat control parameter range over which contrasting requirements of an effective temperature control and a sufficiently low interfacial thermal resistance are simultaneously satisfied. We show that a similar disruption in thermal transport occurs in a single phase system of pure solid atoms as well. We trace the microscopic origin of the anomalous interfacial thermal resistance to a stochastic/frictional forcing-induced alteration in the force autocorrelation function. We propose a simple model consisting of an individual atom impinging in vacuo on a thermostatted solid as a computationally inexpensive alternative for determination of the control parameter range over which thermostat-induced spurious thermal resistance across a solid-liquid interface becomes significant. Our results suggest that the undesirable possibility of MD-deduced temperature jumps being misleading indicators of the interfacial Kapitza resistance could simply be eliminated through a judicious choice of the thermostat control parameter. © 2020 Author(s).

Item Type:	Journal Article
Publication:	Journal of Chemical Physics
Publisher:	American Institute of Physics Inc.
Additional Information:	The copyright of this article belongs to American Institute of Physics Inc.
Keywords:	Liquids; Molecular dynamics; Stochastic systems; Temperature control; Thermostats, Autocorrelation functions; Control temperatures; Effective temperature; Interfacial resistances; Interfacial thermal resistance; Molecular transport; Non equilibrium molecular dynamic (NEMD); Solid-liquid interfaces, Phase interfaces, article; autocorrelation; heat tolerance; molecular dynamics; stochastic model
Department/Centre:	Division of Mechanical Sciences > Mechanical Engineering
Date Deposited:	15 Jan 2021 05:52
Last Modified:	15 Jan 2021 05:52
URI:	http://eprints.iisc.ac.in/id/eprint/67349

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