Evaluation of heat current formulations for equilibrium molecular dynamics calculations of thermal conductivity

2010 ◽  
Vol 132 (10) ◽  
pp. 104111 ◽  
Author(s):  
Alejandro Guajardo-Cuéllar ◽  
David B. Go ◽  
Mihir Sen
Keyword(s):  
Thermal Conductivity ◽  
Molecular Dynamics ◽  
Heat Current ◽  
Molecular Dynamics Calculations

Thermal Conductivity of Individual Single-Wall Carbon Nanotubes

2006 ◽  
Vol 129 (6) ◽  
pp. 705-716 ◽  
Author(s):  
Jennifer R. Lukes ◽  
Hongliang Zhong
Keyword(s):  
Experimental Data ◽  
Thermal Conductivity ◽  
Carbon Nanotubes ◽  
Molecular Dynamics ◽  
Molecular Dynamics Simulation ◽  
Dynamics Simulation ◽  
Single Wall Carbon Nanotubes ◽  
Heat Current ◽  
Single Wall Carbon ◽  
Simulation Methodology

Despite the significant amount of research on carbon nanotubes, the thermal conductivity of individual single-wall carbon nanotubes has not been well established. To date only a few groups have reported experimental data for these molecules. Existing molecular dynamics simulation results range from several hundred to 6600 W∕m K and existing theoretical predictions range from several dozens to 9500 W∕m K. To clarify the several-order-of-magnitude discrepancy in the literature, this paper utilizes molecular dynamics simulation to systematically examine the thermal conductivity of several individual (10, 10) single-wall carbon nanotubes as a function of length, temperature, boundary conditions and molecular dynamics simulation methodology. Nanotube lengths ranging from 5 nm to 40 nm are investigated. The results indicate that thermal conductivity increases with nanotube length, varying from about 10 W∕m to 375 W∕m K depending on the various simulation conditions. Phonon decay times on the order of hundreds of fs are computed. These times increase linearly with length, indicating ballistic transport in the nanotubes. A simple estimate of speed of sound, which does not require involved calculation of dispersion relations, is presented based on the heat current autocorrelation decay. Agreement with the majority of theoretical/computational literature thermal conductivity data is achieved for the nanotube lengths treated here. Discrepancies in thermal conductivity magnitude with experimental data are primarily attributed to length effects, although simulation methodology, stress, and intermolecular potential may also play a role. Quantum correction of the calculated results reveals thermal conductivity temperature dependence in qualitative agreement with experimental data.

Molecular Dynamics Calculations of InSb Thermal Conductivity

2010 ◽  
Vol 297-301 ◽  
pp. 1400-1407
Author(s):  
Giovano de Oliveira Cardozo ◽  
José Pedro Rino
Keyword(s):  
Experimental Data ◽  
Thermal Conductivity ◽  
Molecular Dynamics ◽  
Infinite System ◽  
Thermal Conductivity Coefficient ◽  
Direct Method ◽  
Molecular Dynamics Calculations ◽  
Non Equilibrium Molecular Dynamics ◽  
Three Body ◽  
Non Equilibrium

Equilibrium and non-equilibrium molecular dynamics calculations of thermal conductivity coefficient are presented for bulk systems of InSb, using an effective two- and three-body inter atomic potential which demonstrated to be very transferable. In the calculations, the obtained coefficients were comparable to the experimental data. In the case of equilibrium simulations a Green-Kubo approach was used and the thermal conductivity was calculated for five temperatures between 300 K and 900 K. For the non equilibrium, or direct method, which is based on the Fourier’s law, the thermal conductivity coefficient was determined at a mean temperature of 300K. In this case it was used a pair of reservoirs, placed at a distance L from each other, and with internal temperatures fixed in 250 K, for the cold reservoir, and 350 K for the hot one. In order to obtain an approach to an infinite system coefficient, four different values of L were used, and the data was extrapolated to L→∞.

Molecular Dynamics Simulation of the Thermal Conductivity of Ar-Al Nanofluid Using Simplified Model

2009 ◽  
Author(s):  
Jie Liu ◽  
Wen-Qiang Lu
Keyword(s):  
Thermal Conductivity ◽  
Molecular Dynamics ◽  
Brownian Dynamics ◽  
Base Fluid ◽  
Numerical Results ◽  
Solid Particles ◽  
Dynamics Simulation ◽  
Simplified Model ◽  
Heat Current

Nanofluid is a colloidal solution of nano-sized solid particles in liquids. Ar-Al nanofluid is a promising heat transport fluid in the fields of low-temperature engineering. A simplified model based on the equilibrium molecular dynamics (EMD) simulation is constructed to calculate the thermal conductivity of argon suspension containing aluminum nanoparticles. The numerical method is verified by comparing the numerical results with the existing numerical results and the experimental data of the base fluid. The influence of various nanoparticle loadings is obtained and the results show that the thermal conductivity with 1% nanoparticle loading enhances up to 31% compared with the base fluid. The heat current autocorrelation functions converge well for the basefluid and nanofluid. Furthermore, interesting distinct oscillations are obtained especially at higher nanoparticle loading. The significant role of the interaction between the fluid atoms and the solid nanoparticle rather than Brownian dynamics motion of the nanoparticle in yielding the high thermal conductivity of nanofluid is numerically revealed.

Phonon Thermal Conductivity of the Cubic and Monoclinic Phases of Zirconia by Molecular Dynamics Simulation

2020 ◽  
Vol 843 ◽  
pp. 110-115
Author(s):  
Leila Momenzadeh ◽  
Irina V. Belova ◽  
Graeme E. Murch
Keyword(s):  
Experimental Data ◽  
Thermal Conductivity ◽  
Molecular Dynamics ◽  
Molecular Dynamics Simulation ◽  
Lattice Thermal Conductivity ◽  
Dynamics Simulation ◽  
Heat Current ◽  
Phonon Thermal Conductivity ◽  
Low Thermal Conductivity ◽  
Two Phases

Zirconia has a number of remarkable properties, including a very low thermal conductivity. In this research, the phonon thermal conductivity of two phases (cubic and monoclinic) of zirconia (ZrO2) are calculated. For this purpose, an equilibrium molecular dynamics simulation employing the Green-Kubo formalism is used. The results are presented in detail over a wide temperature range, from 100 K to 2400 K and 100 K to 1400 K for the above-mentioned structures, respectively, with a 100K temperature step. The temperature dependence of the equilibrium atomic volume demonstrated a reasonable agreement with the experimental data. Moreover, the lattice thermal conductivity was calculated by analysing the heat current autocorrelation function. The results showed that zirconia has a low thermal conductivity that is dependent on the temperature. It was also shown that the lattice thermal conductivity of the two phases of zirconia can be decomposed into three contributions due to the acoustic shortrange and long-range phonon and optical phonon modes. Finally, the results from this research are compared with the available experimental data.

Molecular Dynamics Determination of the Lattice Thermal Conductivity of the Cubic Phase of Hafnium Dioxide

2020 ◽  
Vol 27 ◽  
pp. 177-185
Author(s):  
Leila Momenzadeh ◽  
Irina V. Belova ◽  
Graeme E. Murch
Keyword(s):  
Thermal Conductivity ◽  
Molecular Dynamics ◽  
Autocorrelation Function ◽  
Lattice Thermal Conductivity ◽  
Hafnium Dioxide ◽  
Industrial Applications ◽  
Cubic Phase ◽  
Heat Current ◽  
Phonon Modes ◽  
Wide Range

The wide range of industrial applications is the main reason for an increased interest in dioxides such as HfO2. In this study, classical molecular dynamic simulations were performed to calculate the lattice thermal conductivity of the cubic phase of HfO2, over a temperature range of 100-3000 K, based on the Green-Kubo fluctuation method. In this research, the heat current autocorrelation function and lattice thermal conductivity were calculated in the a-direction. The lattice thermal conductivity of the cubic phase of HfO2 was found to be a result of three contributions. These were the optical and acoustic short-range and long-range phonon modes. Comparisons between the results of the research and experimental data when available indicate good agreement. Keywords: lattice thermal conductivity, molecular dynamics, Green-Kubo formalism, heat current autocorrelation function, hafnium dioxid

Thermal Conductivity Estimation of Nano Graphene Using Equilibrium Molecular Dynamics With Andersen and Berendsen Thermostats

2011 ◽  
Author(s):  
Masoud H. Khadem ◽  
Aaron P. Wemhoff
Keyword(s):  
Thermal Conductivity ◽  
Molecular Dynamics ◽  
Potential Model ◽  
Control Method ◽  
Honeycomb Structure ◽  
Heat Current ◽  
Wide Range ◽  
Nano Graphene ◽  
The Impact ◽  
Covalent Interactions

The impact of the temperature control method on the thermal conductivity of a small sheet of graphene is studied. Equilibrium Molecular Dynamics (EMD) simulations are used to evaluate the heat current fluctuations and thermal conductivity calculations. The Tersoff potential model is used to determine the covalent interactions between carbon atoms of the graphene’s honeycomb structure. Green-Kubo relations are employed to estimate thermal conductivity values. Andersen and Berendsen thermostats are separately utilized to obtain a desired temperature for the canonical (NVT) ensemble. The influence of the chosen thermostat on the estimated thermal conductivity found to be significant. The wide range of computational and experimental results shows that further work is required to confidently determine the thermal conductivity of this material.

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