Interatomic potential for predicting the thermal conductivity of zirconium trisulfide monolayers with molecular dynamics

2021 ◽  
Vol 129 (15) ◽  
pp. 155105
Author(s):  
Fernan Saiz ◽  
Yenal Karaaslan ◽  
Riccardo Rurali ◽  
Cem Sevik
Author(s):  
Keivan Esfarjani ◽  
Gang Chen ◽  
Asegun Henry

Based on first-principles density-functional calculations, we have developed and tested a force-field for silicon, which can be used for molecular dynamics simulations and the calculation of its thermal properties. This force field uses the exact Taylor expansion of the total energy about the equilibrium positions up to 4th order. In this sense, it becomes systematically exact for small enough displacements, and can reproduce the thermodynamic properties of Si with high fidelity. Having the harmonic force constants, one can easily calculate the phonon spectrum of this system. The cubic force constants, on the other hand, will allow us to compute phonon lifetimes and scattering rates. Results on equilibrium Green-Kubo molecular dynamics simulations of thermal conductivity as well as an alternative calculation of the latter based on the relaxation-time approximation will be reported. The accuracy and ease of computation of the lattice thermal conductivity using these methods will be compared. This approach paves the way for the construction of accurate bulk interatomic potentials database, from which lattice dynamics and thermal properties can be calculated and used in larger scale simulation methods such as Monte Carlo.


Author(s):  
Carlos J. Gomes ◽  
Marcela Madrid ◽  
Cristina H. Amon

We have implemented a parallel molecular dynamics algorithm, which incorporates the Stillinger-Weber interatomic potential. The code was parallelized using a ghost cell atomic division approach, ensuring scaling with the number of processors and a significant increase in speed with respect to the serial version. The methodology is validated by computing the thermal conductivity and phonon frequency spectra of bulk silicon single crystals for different domain sizes at 1000K. The predicted thermal conductivities are consistent with the experimental value at that temperature. In addition, the phonon frequency spectra capture the properties expected from the dispersion relations for silicon.


2020 ◽  
Vol 9 (1) ◽  
pp. 11-25
Author(s):  
Jude S. Alexander ◽  
Christopher Maxwell ◽  
Jeremy Pencer ◽  
Mouna Saoudi

The ready availability of codes such as LAMMPS (Large-scale Atomic/Molecular Massively Parallel Simulator) for molecular dynamics simulations has opened up the realm of atomistic modelling to novice code users with an interest in computational materials modelling but who lack the appropriate theoretical or computational background. As such, there is significant risk of the “user effect” having a negative impact on the quality of results obtained using such codes. Here, we present a “how-to” procedure for equilibrium molecular dynamics-based nuclear fuel thermal conductivity calculations using the Green–Kubo method with an interatomic potential developed by Cooper et al. [ 1 ]. The various steps of the simulation are identified and explained, along with criteria to assess the quality of the intermediate and final results, discussion of some problems that can arise during a simulation, and some inherent limitations of the method. Calculated thermal conductivities for UO2 and ThO2 will be compared with the available experimental data and also with similar thermal conductivity calculations using nonequilibrium molecular dynamics, reported in the open literature.


Volume 4 ◽  
2004 ◽  
Author(s):  
Xinwei Wang ◽  
Cecil Lawrence

In this work, nonequilibrium molecular dynamics is used to predict the thermal conductivity of nanoscale thin silicon films in the thickness direction. Recently developed environment-dependent interatomic potential for silicon, which offers considerable improvement over the more common Stillinger-Weber potential, is used. Silicon films of various thicknesses are modeled to establish the variation of thermal conductivity with the film thickness. The obtained relationship between the thermal conductivity and the film thickness is compared with the results of the Lattice Boltzmann method, and sound agreement is observed.


2006 ◽  
Vol 128 (11) ◽  
pp. 1114-1121 ◽  
Author(s):  
Carlos J. Gomes ◽  
Marcela Madrid ◽  
Javier V. Goicochea ◽  
Cristina H. Amon

The thermal conductivity of silicon thin films is predicted in the directions parallel and perpendicular to the film surfaces (in-plane and out-of-plane, respectively) using equilibrium molecular dynamics, the Green-Kubo relation, and the Stillinger-Weber interatomic potential. Three different boundary conditions are considered along the film surfaces: frozen atoms, surface potential, and free boundaries. Film thicknesses range from 2to217nm and temperatures from 300to1000K. The relation between the bulk phonon mean free path (Λ) and the film thickness (ds) spans from the ballistic regime (Λ⪢ds) at 300K to the diffusive, bulk-like regime (Λ⪡ds) at 1000K. When the film is thin enough, the in-plane and out-of-plane thermal conductivity differ from each other and decrease with decreasing film thickness, as a consequence of the scattering of phonons with the film boundaries. The in-plane thermal conductivity follows the trend observed experimentally at 300K. In the ballistic limit, in accordance with the kinetic and phonon radiative transfer theories, the predicted out-of-plane thermal conductivity varies linearly with the film thickness, and is temperature-independent for temperatures near or above the Debye’s temperature.


2005 ◽  
Author(s):  
Carlos J. Gomes ◽  
Marcela Madrid ◽  
Javier V. Goicochea ◽  
Cristina H. Amon

The thermal conductivity of silicon thin films is predicted in the directions parallel and perpendicular to the film surfaces (in-plane and out-of-plane, respectively) using equilibrium molecular dynamics, the Green-Kubo relationship and the Stillinger-Weber interatomic potential. Film thicknesses range from 2 to 220 nm and temperatures from 300 to 1000 K. In this range of temperatures, the relation between the phonon mean free path (Λ) and the film thickness (ds) spans from the ballistic regime (≫ ds) to the diffusive, bulk-like regime (≪ ds). We show that equilibrium molecular dynamics and the Green-Kubo relationship can be applied to the study of the thermal conductivity of thin films in the ballistic, transitional and diffusive regimes. When the film is thin enough, the thermal conductivity becomes orthotropic and decreases with decreasing film thickness as a consequence of the scattering of phonons with the film boundaries. The in-plane thermal conductivity follows the trend observed experimentally at 300 K. In the ballistic limit, in accordance with the kinetic theory, the predicted out-of-plane thermal conductivity varies linearly with the film thickness and is temperature-independent for temperatures near or above Debye’s temperature.   This paper was also originally published as part of the Proceedings of the ASME 2005 Pacific Rim Technical Conference and Exhibition on Integration and Packaging of MEMS, NEMS, and Electronic Systems.


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