Multicanonical Molecular Dynamics Simulation Study of the Liquid-Solid and Solid-Solid Transitions in Lennard-Jones Clusters

2011 ◽  
Author(s):  
Toshihiro Kaneko ◽  
Kenji Yasuoka ◽  
Ayori Mitsutake ◽  
Xiao Cheng Zeng
Keyword(s):  
Molecular Dynamics ◽  
Heat Capacity ◽  
Transition Temperature ◽  
Peak Position ◽  
Temperature Curve ◽  
Dynamics Simulation ◽  
Lennard Jones ◽  
Dynamics Simulations ◽  
First Time ◽  
Good Agreement

Multicanonical molecular dynamics simulations are applied, for the first time, to study the liquid-solid and solid-solid transitions in Lennard-Jones (LJ) clusters. The transition temperatures are estimated based on the peak position in the heat capacity versus temperature curve. For LJ31, LJ58 and LJ98, our results on the solid-solid transition temperature are in good agreement with previous ones. For LJ309, the predicted liquid-solid transition temperature is also in agreement with previous result.

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.

A Molecular Dynamics Simulation for Thermal Conductivity Evaluation of Carbon Nanotube-Water Nanofluids

2013 ◽  
Vol 135 (4) ◽  
Author(s):  
M. J. Javanmardi ◽  
K. Jafarpur
Keyword(s):  
Thermal Conductivity ◽  
Molecular Dynamics ◽  
Carbon Nanotube ◽  
Liquid Water ◽  
Dynamics Simulation ◽  
Effect Of Temperature ◽  
Jones Potential ◽  
Lennard Jones ◽  
Walled Carbon Nanotubes ◽  
Good Agreement

A nanofluid model is simulated by molecular dynamics (MD) approach. The simulated nanofluid has been a dispersion of single walled carbon nanotubes (CNT) in liquid water. Intermolecular force in liquid water has been determined using TIP4P model, and, interatomic force due to carbon nanotube has been calculated by the simplified form of Brenner's potential. However, interaction between molecules of water and atoms of carbon nanotube is modeled by Lennard-Jones potential. The Green–Kubo method is employed to predict the effective thermal conductivity of the nanofluid, and, effect of temperature is sought. The obtained results are checked against experimental data, and, good agreement between them is observed.

scholarly journals Ab Initio Molecular Dynamics Simulation of Tribochemical Reactions Involving Phosphorus Additives at Sliding Iron Interfaces

2018 ◽  
Author(s):  
Sophie Loehlé ◽  
M. C. Righi
Keyword(s):  
Molecular Dynamics ◽  
Ab Initio ◽  
Dynamics Simulation ◽  
Ab Initio Molecular Dynamics ◽  
Molecular Dissociation ◽  
Iron Phosphide ◽  
Dynamics Simulations ◽  
Activation Times ◽  
First Time ◽  
Dissociation Barrier

We performed for the first time to our knowledge fully ab initio molecular dynamics simulations of additive tribochemistry in boundary lubrication conditions. We consider an organophosphourus additive that has been experimentally shown to reduce friction in steel-on-steel sliding contacts thanks to the tribologically-induced formation of an iron phosphide tribofilm. The simulations allow us to observe in real time the molecular dissociation at the sliding iron interface under pressure and to understand the mechanism of iron phosphide formation. We discuss the role played by the mechanical stress by comparing the activation times for molecular dissociation observed in the tribological simulations at different applied loads with that expected on the basis of the dissociation barrier.

Acceleration of molecular dynamics simulation of multiphase systems on GPU

2012 ◽  
Vol 9 (2) ◽  
pp. 76-79
Author(s):  
D.F. Marin
Keyword(s):  
Molecular Dynamics ◽  
Molecular Dynamics Simulation ◽  
Molecular Dynamics Simulations ◽  
Intermolecular Interaction ◽  
Dynamics Simulation ◽  
Water Molecules ◽  
Lennard Jones ◽  
Multiphase Systems ◽  
And Performance ◽  
Dynamics Simulations

The paper presents results on acceleration of molecular dynamics simulations with the usage of GPUs. A system of water molecules is considered as an example of polar liquid. The intermolecular interaction is modeled with the usage of Coulomb and truncated Lennard-Jones potentials. Results of computational experiments on acceleration and performance of the developed code are presented.

Molecular Dynamics Simulation on Transformation-Induced Plastic Deformation Using a Lennard-Jones Model

2014 ◽  
Vol 626 ◽  
pp. 414-419 ◽  
Author(s):  
Takuya Uehara
Keyword(s):  
Molecular Dynamics ◽  
Phase Transformation ◽  
External Load ◽  
Local Stress ◽  
Dynamics Simulation ◽  
Transformation Plasticity ◽  
Preliminary Calculation ◽  
Lennard Jones ◽  
Specific Strain ◽  
Dynamics Simulations

Molecular dynamics simulations were carried out to clarify the atomistic mechanism of transformation plasticity. As the first step for the purpose, a simple thin-film model consisting of 8640 atoms was prepared. Phase transformation was assumed to be expressed by switching the material parameters of Lennard-Jones potential function. As a preliminary calculation, phase transformation was forced to occur homogeneously in the whole region of the model, resulting in no extra strain except volumetric transformation dilatation. In that case, perfect single crystal structure was maintained in the new phase. Simulations were carried out under external load, but specific strain was not generated. On the contrary, when the transformation region was set partially in the model and the region was expanded with time, a large deformation was observed. In the middle process of the phase transformation, slip-like deformation behavior and the change in crystal orientation occurred, indicating that extra plastic strain was induced during phase transformation. The strain was observed even when external load is not applied, and hence it was concluded that not only external load but also local stress distribution may cause the transformation plasticity.

scholarly journals Thermal and Caloric Properties of Fluids from Non-equilibrium Molecular Dynamics Simulations using the Two-gradient Method

2021 ◽  
Author(s):  
Martin P. Lautenschläger ◽  
Hans Hasse
Keyword(s):  
Molecular Dynamics ◽  
Heat Capacity ◽  
Thermal Expansion ◽  
Molecular Dynamics Simulations ◽  
Transport Properties ◽  
Thermal Expansion Coefficient ◽  
Gradient Method ◽  
Lennard Jones ◽  
Non Equilibrium Molecular Dynamics ◽  
Dynamics Simulations

Transport properties of fluids can be determined efficiently from non-equilibrium molecular dynamics simulations using the two-gradient method which was introduced recently. It is shown here that also thermal and caloric properties of fluids can be determined accurately and efficiently along with the transport properties using this method. In a single run, all these properties are obtained for a series of state points at different temperatures and constant pressure. The truncated and shifted Lennard-Jones (LJTS) fluid is studied here as a test case. Data are reported for about 700 state points in the range of (T = [0:7; 8:5] and ? = [0:2; 1:0]). Besides data on the thermal conductivity, shear viscosity, and selfdiffusion the following thermal and caloric properties were measured: pressure p, internal energy u, enthalpy h, isobaric heat capacity cp and thermal expansion coefficient ?p. The results of the thermal and caloric properties agree very well with those from an accurate equation of state from the literature. Also the shear rate dependence of these properties can be studied easily with the two-gradient method. Keywords: local equilibrium; Lennard-Jones fluid; isobaric heat capacity; thermal expansion coefficient

The Structure and Properties of Vicinal Water

1990 ◽  
Vol 197 ◽  
Author(s):  
Frank M. Etzler ◽  
James J. Conners ◽  
Russell F. Ross
Keyword(s):  
Molecular Dynamics ◽  
Heat Capacity ◽  
Molecular Dynamics Simulation ◽  
Thermodynamic Properties ◽  
Thermodynamic Model ◽  
Geometric Analysis ◽  
Dynamics Simulation ◽  
Statistical Thermodynamic ◽  
Structure And Properties ◽  
Dynamics Simulations

ABSTRACTThe properties of water near surfaces are known to differ from those of the bulk. For instance, in 140 A diameter silica pores the density has been found to be 3% lower than that of the bulk while the heat capacity is 25% greater than that the bulk. Etzler [15] has proposed a statistical thermodynamic model for vicinal water. This model has been able to correlate a number of thermodynamic properties of water in silica pores. Furthermore, some of the microscopic implications of the model have been found to be consistent with molecular dynamics simulations. Here we discuss the results of a statistical geometric analysis of a molecular dynamics simulation which, as first suggested by Roentgen (1892), indicates that water indeed exists in “bulky” and “dense” states. Furthermore, recent results concerning the temperature dependence of the heat capacity of water in silica pores is discussed.

scholarly journals Employing Hybrid Lennard-Jones and Axilrod-Teller Potentials to Parametrize Force Fields for the Simulation of Materials’ Properties

Materials ◽  
2021 ◽  
Vol 14 (21) ◽  
pp. 6352
Author(s):  
Danilo de Camargo Branco ◽  
Gary J. Cheng
Keyword(s):  
Molecular Dynamics ◽  
Material Properties ◽  
Force Fields ◽  
Ambient Conditions ◽  
Materials Properties ◽  
Materials Behaviors ◽  
Lennard Jones ◽  
Computational Materials ◽  
Dynamics Simulations ◽  
First Time

The development of novel materials has challenges besides their synthesis. Materials such as novel MXenes are difficult to probe experimentally due to their reduced size and low stability under ambient conditions. Quantum mechanics and molecular dynamics simulations have been valuable options for material properties determination. However, computational materials scientists may still have difficulty finding specific force field models for their simulations. Force fields are usually hard to parametrize, and their parameters’ determination is computationally expensive. We show the Lennard-Jones (2-body interactions) combined with the Axilrod-Teller (3-body interactions) parametrization process’ applicability for metals and new classes of materials (MXenes). Because this parametrization process is simple and computationally inexpensive, it allows users to predict materials’ behaviors under close-to-ambient conditions in molecular dynamics, independent of pre-existing potential files. Using the process described in this work, we have made the Ti2C parameters set available for the first time in a peer-reviewed work.

Heat Capacity of Nanoconfined Liquid: A Molecular Dynamics Simulation

2017 ◽  
Author(s):  
Rifat Mahmud ◽  
A. K. M. Monjur Morshed ◽  
Titan C. Paul
Keyword(s):  
Molecular Dynamics ◽  
Heat Capacity ◽  
Molecular Dynamics Simulation ◽  
Molar Heat Capacity ◽  
Molecular Model ◽  
Solid Surfaces ◽  
Dynamics Simulation ◽  
Bulk Liquid ◽  
Liquid Domain ◽  
Lennard Jones

Equilibrium molecular dynamics (EMD) simulations aiming to investigate the effect of confinement gap thickness on constant volume molar heat capacity (Cv) of the confined liquid in nanoscale have been carried out by simultaneously controlling the density and temperature of the liquid domain. Simplified Lennard-Jones (LJ) molecular model is used to model the system where the liquid is entrapped between two flat solid surfaces separated by a distance varying from 0.585 nm to 27.8 nm. Molar heat capacity of the bulk liquid has been evaluated using fluctuation formula which matches greatly with the NIST data and published literatures. But in case of confined liquid, molar heat capacity is observed to vary significantly with the gap thickness. For a specific range of gap thickness, molar heat capacity of the confined liquid is found higher than that of the bulk. But molar heat capacity of the nanogap confined liquid becomes independent of the gap thickness and approaches to that of the bulk liquid as gap thickness is greater than this specific range (6.14 nm for 100 K temperature of the confined liquid).

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