Molecular Dynamics Study of the Interfacial Thermal Conductance at the Graphene/Paraffin Interface in Solid and Liquid Phases

2013 ◽  
Author(s):  
Hasan Babaei ◽  
Pawel Keblinski ◽  
J. M. Khodadadi
Keyword(s):  
Molecular Dynamics ◽  
Solid Phase ◽  
Thermal Conductance ◽  
Md Simulations ◽  
Interfacial Thermal Conductance ◽  
A Value ◽  
Number Of Layers ◽  
Liquid Phases ◽  
Phase Systems ◽  
Parallel Configuration

By utilizing molecular dynamics (MD) simulations, we study the interfacial thermal conductance at the interface of graphene and paraffin. In doing so, we conduct non-equilibrium heat source and sink simulations on systems of parallel and perpendicular configurations in which the heat flow is parallel and perpendicular to the surface of graphene, respectively. For the perpendicular configuration, graphene with different number of layers are considered. The results show that the interfacial thermal conductance decreases with the number of layers and converges to a value which is equal to the obtained conductance by using the parallel configuration. We also study the conductance for the solid phase paraffin. The results indicate that solid paraffin-graphene interfaces have higher conductance values with respect to the corresponding liquid phase systems.

scholarly journals Enhancement of Interfacial Thermal Conductance of SiC by Overlapped Carbon Nanotubes and Intertube Atoms

2017 ◽  
Vol 139 (5) ◽  
Author(s):  
Chengcheng Deng ◽  
Xiaoxiang Yu ◽  
Xiaoming Huang ◽  
Nuo Yang
Keyword(s):  
Carbon Nanotubes ◽  
Molecular Dynamics ◽  
Silicon Carbide ◽  
Density Of States ◽  
Probability Distributions ◽  
Thermal Conductance ◽  
Nonequilibrium Molecular Dynamics ◽  
Vibrational Density Of States ◽  
Interfacial Thermal Conductance ◽  
Vibrational Density

A new way was proposed to enhance the interfacial thermal conductance (ITC) of silicon carbide (SiC) composite through the overlapped carbon nanotubes (CNTs) and intertube atoms. By nonequilibrium molecular dynamics (NEMD) simulations, the dependence of ITC on both the number of intertube atoms and the temperature was studied. It is indicated that the ITC can be significantly enhanced by adding intertube atoms and finally becomes saturated with the increase of the number of intertube atoms. And the mechanism is discussed by analyzing the probability distributions of atomic forces and vibrational density of states (VDOS). This work may provide some guidance on enhancing the ITC of CNT-based composites.

scholarly journals Interfacial Thermal Conductance across Graphene/MoS2 van der Waals Heterostructures

Energies ◽  
2020 ◽  
Vol 13 (21) ◽  
pp. 5851
Author(s):  
Shuang Wu ◽  
Jifen Wang ◽  
Huaqing Xie ◽  
Zhixiong Guo
Keyword(s):  
Thermal Conductivity ◽  
First Principles ◽  
Van Der Waals ◽  
Thermal Conductance ◽  
Md Simulations ◽  
Monolayer Graphene ◽  
Density Of State ◽  
Interfacial Thermal Conductance ◽  
Van Der Waals Heterostructure ◽  
Phonon Spectra

The thermal conductivity and interface thermal conductance of graphene stacked MoS2 (graphene/MoS2) van der Waals heterostructure were studied by the first principles and molecular dynamics (MD) simulations. Firstly, two different heterostructures were established and optimized by VASP. Subsequently, we obtained the thermal conductivity (K) and interfacial thermal conductance (G) via MD simulations. The predicted Κ of monolayer graphene and monolayer MoS2 reached 1458.7 W/m K and 55.27 W/m K, respectively. The thermal conductance across the graphene/MoS2 interface was calculated to be 8.95 MW/m2 K at 300 K. The G increases with temperature and the interface coupling strength. Finally, the phonon spectra and phonon density of state were obtained to analyze the changing mechanism of thermal conductivity and thermal conductance.

scholarly journals Characterizing Moisture Uptake and Plasticization Effects of Water on Amorphous Amylose Starch Models Using Molecular Dynamics Methods

2020 ◽  
Author(s):  
Jeffrey Sanders ◽  
Mayank Misra ◽  
Thomas JL Mustard ◽  
David J. Giesen ◽  
Teng Zhang ◽  
...  
Keyword(s):  
Molecular Dynamics ◽  
Moisture Content ◽  
Force Field ◽  
Moisture Sorption ◽  
Md Simulations ◽  
A Value ◽  
Moisture Sorption Isotherm ◽  
Molecular Dynamics Methods ◽  
Grand Canonical ◽  
Good Agreement

<p>Dynamics and thermophysical properties of amorphous starch were explored using molecular dynamics (MD) simulations. Using the OPLS3e force field, simulations of short amylose chains in water were performed to determine force field accuracy. Using well-tempered metadynamics, a free energy map of the two glycosidic angles of an amylose molecule was constructed and compared with other modern force fields. Good agreement of torsional sampling for both solvated and amorphous amylose starch models was observed. Using combined grand canonical Monte Carlo (GCMC)/MD simulations, a moisture sorption isotherm curve is predicted along with temperature dependence. Concentration-dependent activation energies for water transport agree quantitatively with previous experiments. Finally, the plasticization effect of moisture content on amorphous starch was investigated. Predicted glass transition temperature (Tg) depression as a function of moisture content is in line with experimental trends. Further, our calculations provide a value for the dry Tg for amorphous starch, a value which no experimental value is available.</p><div><br></div>

scholarly journals Atomistic Nodal Approach: a General Molecular Dynamics Method For Computing Local Thermal Conductance at Atomistic Resolution

2021 ◽  
Author(s):  
Mingxuan Jiang ◽  
Juan D. Olarte-Plata ◽  
Fernando Bresme
Keyword(s):  
Molecular Dynamics ◽  
Thermal Transport ◽  
Temperature Drop ◽  
Thermal Conductance ◽  
Fundamental Property ◽  
Lower Surface ◽  
Coordination Numbers ◽  
Interfacial Thermal Conductance ◽  
Non Equilibrium Molecular Dynamics ◽  
Dynamics Simulations

The Interfacial Thermal Conductance (ITC) is a fundamental property of mate- rials and has particular relevance at the nanoscale. The ITC quanti�es the thermal resistance between materials of dierent compositions or between uids in contact with materials. Furthermore, the ITC determines the rate of cooling/heating of the materi- als and the temperature drop across the interface. Here we propose a method to com- pute local ITCs and temperature drops of nanoparticle- uid interfaces. Our approach resolves the ITC at the atomic level using the atomic coordinates of the nanomaterial as nodes to compute local thermal transport properties. We obtain high-resolution descriptions of the interfacial thermal transport by combining the atomistic nodal ap- proach, computational geometry techniques and \computational farming" using Non- Equilibrium Molecular Dynamics simulations. We illustrate our method by analyzing various nanoparticles as a function of their size and geometry, targeting experimentally relevant structures like capped octagonal rods, cuboctahedrons, decahedrons, rhombic dodecahedrons, cubes, icosahedrons, truncated octahedrons, octahedrons and spheres. We show that the ITC of these very dierent geometries can be accurately described in terms of the local coordination number of the atoms in the nanoparticle surface. Nanoparticle geometries with lower surface coordination numbers feature higher ITCs, and the ITC generally increases with decreasing particle size.

scholarly journals Molecular Dynamics Simulations of Hexane Deposited onto Graphite: An Explicit–Hydrogen Model at ρ = 1

2007 ◽  
Vol 6 (1) ◽  
Author(s):  
M Connolly ◽  
M Roth ◽  
Carlos Wexler ◽  
Paul Gray
Keyword(s):  
Molecular Dynamics ◽  
Solid Phase ◽  
Orientational Order ◽  
Md Simulations ◽  
Thermal Fluctuations ◽  
Melting Behavior ◽  
Negative Energy ◽  
Graphite Substrate ◽  
Open Questions ◽  
Dynamics Simulations

We present the results of parallel Molecular Dynamics computer simulations of hexane (C6H14) adlayers physisorbed onto a graphite substrate in the density range 0.5 ≤ ρ ≤1 in units of monolayers, with emphasis on monolayer completion (ρ = 1). The hexane molecules are modeled to explicitly include hydrogens and the graphite is modeled as a six – layer all atom structure. In the explicit hydrogen simulations, the herringbone solid loses its orientational order at T1 = 140 °K, fairly consistent with results of UA simulations. However there is almost no nematic meso-phase or negative energy change at the loss of herringbone order. The explicit hydrogen melting temperature is T2 = 160 °K—somewhat lower than seen in experiment and in UA simulations. Generally, results for the all–atom model agree well with experiment, as the molecules remain overall flat on the substrate in the solid phase. At densities below about ρ = 0.875 the system supports a connected network which stabilizes it against thermal fluctuations and yields much more reasonable sub-monolayer- melting behavior. The united atom picture, on the other hand, departs significantly from experiment at most sub-monolayer- densities and gives melting temperatures several decades below what is experimentally observed. The purpose of this work is to compare the results of UA and explicit hydrogen MD simulations of hexane on graphite mainly at ρ = 1, to discuss cursory explorations at sub-monolayer- densities and mention open questions related to the system that are worth pursuing. Various structural and thermodynamic order parameters and distributions are presented in order to outline such differences.

scholarly journals Characterizing Moisture Uptake and Plasticization Effects of Water on Amorphous Amylose Starch Models Using Molecular Dynamics Methods

2020 ◽  
Author(s):  
Jeffrey Sanders ◽  
Mayank Misra ◽  
Thomas JL Mustard ◽  
David J. Giesen ◽  
Teng Zhang ◽  
...  
Keyword(s):  
Molecular Dynamics ◽  
Moisture Content ◽  
Force Field ◽  
Moisture Sorption ◽  
Md Simulations ◽  
A Value ◽  
Moisture Sorption Isotherm ◽  
Molecular Dynamics Methods ◽  
Grand Canonical ◽  
Good Agreement

<p>Dynamics and thermophysical properties of amorphous starch were explored using molecular dynamics (MD) simulations. Using the OPLS3e force field, simulations of short amylose chains in water were performed to determine force field accuracy. Using well-tempered metadynamics, a free energy map of the two glycosidic angles of an amylose molecule was constructed and compared with other modern force fields. Good agreement of torsional sampling for both solvated and amorphous amylose starch models was observed. Using combined grand canonical Monte Carlo (GCMC)/MD simulations, a moisture sorption isotherm curve is predicted along with temperature dependence. Concentration-dependent activation energies for water transport agree quantitatively with previous experiments. Finally, the plasticization effect of moisture content on amorphous starch was investigated. Predicted glass transition temperature (Tg) depression as a function of moisture content is in line with experimental trends. Further, our calculations provide a value for the dry Tg for amorphous starch, a value which no experimental value is available.</p><div><br></div>

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