Molecular Dynamics Simulation of Phonon Transport in EDIP Silicon

2005 ◽  
Author(s):  
Lin Sun ◽  
Jayathi Y. Murthy
Keyword(s):  
Thermal Conductivity ◽  
Molecular Dynamics ◽  
Relaxation Times ◽  
Domain Size ◽  
Single Mode ◽  
Phonon Transport ◽  
Dispersion Curves ◽  
Dynamics Simulation ◽  
Dynamical Matrix ◽  
Bulk Silicon

In this paper, molecular dynamics (MD) simulation is employed to compute thermal conductivity, dispersion curves and single mode relaxation times for bulk silicon. A newly-developed environment-dependent interatomic potential (EDIP) is used in our simulations. Using the Green-Kubo method, simulations of bulk silicon thermal conductivity are conducted using 216 to 4096 atoms. The effect of domain size is explored for different temperatures. Thermal conductivity predictions are found to converge to a bulk value for simulations containing 1000 atoms or more, even though the domain is much smaller than the phonon mean free path. A domain-size independent thermal conductivity is computed for temperatures ranging from 300 K to 1000 K and is shown to compare reasonably well with experimental data without the need for correction factors. The MD results are analyzed to obtain phonon dispersion curves along the [100] direction. Dispersion curves are also obtained using EDIP under a harmonic approximation and the classical dynamical matrix approach. The two sets of curves agree reasonably well. Furthermore, single mode phonon relaxation times are computed from the MD simulations. The trend can be curve-fit by third or fourth-order polynomials.

Coupling Between Phonons and Fluid Particles in Water/Carbon Nanotube Systems

2009 ◽  
Author(s):  
A. J. H. McGaughey ◽  
J. A. Thomas ◽  
J. Turney ◽  
R. M. Iutzi
Keyword(s):  
Thermal Conductivity ◽  
Molecular Dynamics ◽  
Carbon Nanotube ◽  
Relaxation Times ◽  
Mean Free Path ◽  
Phonon Transport ◽  
Dynamics Simulation ◽  
Spectral Energy ◽  
Total Thermal Conductivity ◽  
Phonon Modes

We investigate thermal transport in water/carbon nanotube (CNT) composite systems using molecular dynamics simulations. Carbon-carbon interactions are modeled using the second-generation REBO potential, water-water interactions are modeled using the TIP4P potential, and carbon-water interactions are modeled using a Lennard-Jones potential. The thermal conductivities of empty and water-filled CNTs with diameters between 0.83 nm and 1.66 nm are predicted using molecular dynamics simulation and a direct application of the Fourier law. For empty CNTs, the thermal conductivity decreases with increasing CNT diameter. As the CNT length approaches 1 micron, a length-independent thermal conductivity is obtained, indicative of diffusive phonon transport. When the CNTs are filled with water, the thermal conductivity decreases compared to the empty CNTs and transitions to diffusive phonon transport at shorter lengths. To understand this behavior, we calculate the spectral energy density of the empty and water-filled CNTs and calculate the mode-specific group velocities, relaxation times, and thermal conductivity. For the empty 1.10 nm diameter CNT, we show that the acoustic phonon modes account for 65 percent of the total thermal conductivity. This behavior is attributed to their long mean-free paths. When the CNT is filled with water, interactions with the water molecules shorten the acoustic mode mean-free path and lower the overall CNT thermal conductivity.

Thermal Conductivity of Silicon Thin Films Predicted by Molecular Dynamics Simulations and Theoretical Calculation

2011 ◽  
Vol 55-57 ◽  
pp. 1152-1155 ◽  
Author(s):  
Xing Li Zhang ◽  
Zhao Wei Sun
Keyword(s):  
Thermal Conductivity ◽  
Molecular Dynamics ◽  
Boltzmann Transport Equation ◽  
Phonon Transport ◽  
Dynamics Simulation ◽  
Boltzmann Transport ◽  
Silicon Thin Films ◽  
Simulation Results ◽  
Dynamics Simulations ◽  
Good Agreement

Molecular, dynamics simulation and the Boltzmann transport equation are used respectively to analyze the phonon transport in Si thin film. The MD result is in good agreement with the theoretical analysis values. The results show that the calculated thermal conductivity decreases almost linearly as the film thickness reduced and is almost independent of the temperature at the nanoscale. It was observed from the simulation results that there exists the obvious size effect on the thermal conductivity.

Thermal Conductivity and Phonon Transport Properties of Silicon Using Perturbation Theory and the Environment-Dependent Interatomic Potential

2009 ◽  
Author(s):  
Jose´ A. Pascual-Gutie´rrez ◽  
Jayathi Y. Murthy ◽  
Raymond Viskanta
Keyword(s):  
Thermal Conductivity ◽  
Perturbation Theory ◽  
Carrier Transport ◽  
Interatomic Potential ◽  
Relaxation Times ◽  
Momentum Conservation ◽  
Phonon Transport ◽  
Boltzmann Transport ◽  
Bulk Silicon ◽  
Energy And Momentum

Perturbation theory is used to compute the strength of three-phonon and isotope scattering mechanisms in silicon using the Environment-Dependent Interatomic Potential (EDIP) without resorting to any parameter-fitting. A detailed methodology to accurately find three-phonon processes satisfying energy- and momentum-conservation rules is described. Bulk silicon thermal conductivity values are computed across a range of temperatures and shown to match experimental data well. It is found that about two-thirds of the heat transport in bulk silicon may be attributed to transverse acoustic modes. Effective relaxation times and mean free paths are computed in order to provide a more complete picture of the detailed transport mechanisms and for use with carrier transport models based on the Boltzmann transport equation.

Thermal Conductivity of Water/Carbon Nanotube Composite Systems: Insights From Molecular Dynamics Simulations

2009 ◽  
Author(s):  
J. A. Thomas ◽  
R. M. Iutzi ◽  
A. J. H. McGaughey
Keyword(s):  
Thermal Conductivity ◽  
Molecular Dynamics ◽  
Carbon Nanotube ◽  
Effective Thermal Conductivity ◽  
Linear Response Theory ◽  
Phonon Transport ◽  
Dynamics Simulation ◽  
Phonon Modes ◽  
Composite Systems ◽  
Dynamics Simulations

The effective thermal conductivity of water/carbon nanotube (CNT) composite systems is predicted using molecular dynamics simulation. Both empty and water-filled CNTs with diameters ranging from 0.83 nm to 1.26 nm are considered. Using a direct application of the Fourier law, we explore the transition to diffusive phonon transport with increasing CNT length and identify the correlation between CNT diameter and fully-diffusive thermal conductivity. Using Green-Kubo linear response theory, we explore how the thermal conductivity of water inside CNT varies with tube diameter. We predict the effective thermal conductivity of the composite systems and examine how the phonon modes in the CNT are affected by interactions with the water molecules.

Study of lattice thermal conductivity of tungsten containing bubbles by molecular dynamics simulation

2020 ◽  
Vol 161 ◽  
pp. 112004
Author(s):  
Hongyu Zhang ◽  
Jizhong Sun ◽  
Yingmin Wang ◽  
Thomas Stirner ◽  
Ali Y. Hamid ◽  
...  
Keyword(s):  
Thermal Conductivity ◽  
Molecular Dynamics ◽  
Molecular Dynamics Simulation ◽  
Lattice Thermal Conductivity ◽  
Dynamics Simulation
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