The Formation and Migration Energy of Bivacancy in fcc Metals

2018 ◽  
Vol 30 ◽  
pp. 11-16
Author(s):  
Gennady M. Poletaev ◽  
Irina V. Zorya ◽  
Mikhail D. Starostenkov
Keyword(s):  
Experimental Data ◽  
Molecular Dynamics ◽  
Diffusion Coefficient ◽  
Formation Energy ◽  
Migration Energy ◽  
Fcc Metals ◽  
Sublimation Energy ◽  
And Migration ◽  
Minimum Work ◽  
Dynamics Method

In the work we propose a method for determining of the formation energy of bivacancy using molecular dynamics method. The key moment of the method for determining of the formation energy of bivacancy is the use of the value ζ, the minimum work that must be spent to remove one atom to infinity from the kink in the monatomic step on the surface of the crystal, calculated indirectly through the experimental data on the formation energy of the vacancy and the sublimation energy. The energy of migration of bivacancy in the work was determined from the temperature dependence of the diffusion coefficient when one bivacancy was introduced into the calculation block.

Determination of surface tension by molecular dynamics methods for monatomic substances

2014 ◽  
Vol 10 ◽  
pp. 73-77
Author(s):  
V.L. Malyshev ◽  
D.F. Maryin ◽  
E.F. Moiseeva ◽  
N.A. Gumerov ◽  
I.Sh. Akhatov
Keyword(s):  
Experimental Data ◽  
Molecular Dynamics ◽  
Surface Tension ◽  
Interaction Potential ◽  
Numerical Results ◽  
Molecular Dynamics Method ◽  
Gas System ◽  
Molecular Dynamics Methods ◽  
Dynamics Method

The results of the calculation of surface tension by the molecular dynamics method for the liquid-gas system based on the example of argon are presented in the article. The method was verified by comparing numerical results with experimental data. The results on the determination of the optimal trimming radius for the interaction potential are presented.

Calculation of Material Properties Using Molecular Dynamics Simulation

2007 ◽  
Author(s):  
Y. H. Park ◽  
J. Tang
Keyword(s):  
Molecular Dynamics ◽  
Molecular Dynamics Simulation ◽  
Melting Point ◽  
Material Properties ◽  
Morse Potential ◽  
Formation Energy ◽  
Dynamics Simulation ◽  
Embedded Atom Method ◽  
Embedded Atom ◽  
Dynamics Method

This paper describes the calculation of material properties of copper (Cu) using the molecular dynamics method. Vacancy formation energy, bulk modulus, surface energy and melting point are calculated using different potentials such as the Morse potential and Embedded Atom Method (EAM). Results obtained from different potentials are discussed and compared with experimental results.

Diffusion Mechanisms in Bcc-Zr:A Molecular Dynamics Approach

1990 ◽  
Vol 209 ◽  
Author(s):  
F. Willaime ◽  
C. Massobrio
Keyword(s):  
Activation Energy ◽  
Molecular Dynamics ◽  
Diffusion Coefficient ◽  
Interatomic Potential ◽  
Migration Energy ◽  
Vacancy Migration ◽  
Migration Mechanism ◽  
Diffusion Mechanisms ◽  
Dynamics Simulations ◽  
Bcc Phase

ABSTRACTBasing our calculations on a realistic N-body interatomic potential for Zr, we study the vacancy migration mechanism and determine the related diffusion coefficient in the bcc phase. The form of the potential energy along the nearest-neighborjump migration path is single-peaked. The vacancy jump rate determined by molecular dynamics simulations has a perfectly Arrhenian behavior and its activation energy is very close to the static value of the vacancy migration energy, both being very low (≈ 0.3 eV) . The diffusion coefficient is in very satisfactory agreement with experiments.

Computer Simulation of Diffusion in Dilute Al-Fe Alloys

2009 ◽  
Vol 289-292 ◽  
pp. 733-740 ◽  
Author(s):  
Mikhail Mendelev ◽  
Alexey Rodin ◽  
Boris S. Bokstein
Keyword(s):  
Experimental Data ◽  
Molecular Dynamics ◽  
Computer Simulation ◽  
Satisfactory Agreement ◽  
Formation Energy ◽  
Activation Energies ◽  
Vacancy Formation Energy ◽  
Vacancy Formation ◽  
Dilute Alloys ◽  
Fe Alloys

We present results of the molecular dynamics study of Al selfdiffusion, Al and Fe diffusion in Al-Fe dilute alloys. We found that addition of Fe does not change the vacancy formation energy but considerably slows down Al diffusion. We also found that Al and Fe migration energies, i.e. energies of vacancy exchange with Al and Fe atoms, differ very strongly. Both activation energies for Al and Fe diffusion are in satisfactory agreement with available experimental data.

Melting curves of Cu, Pt, Pd and Au under high pressures

2016 ◽  
Vol 30 (05) ◽  
pp. 1650013 ◽  
Author(s):  
Baoling Zhang ◽  
Baowen Wang ◽  
Qingxin Liu
Keyword(s):  
Experimental Data ◽  
Molecular Dynamics ◽  
High Pressures ◽  
Melting Curve ◽  
Interaction Forces ◽  
Metal Atoms ◽  
Melting Curves ◽  
Simulation Results ◽  
Dynamics Method ◽  
Good Agreement

Melting curves of Cu, Pt, Pd and Au were calculated via the molecular dynamics method in the temperature range of [Formula: see text]1000–5000 K. The simulation results were compared with the recent high pressure experimental data reported by Errandonea, and the obtained melting curves of Cu, Pt and Au were all in good agreement with his results. For Pd, there were some differences between the obtained melting curve and the experimental data and these differences increased with decreasing temperature to about 7 GPa at 2000 K. The effects of the interaction forces between metal atoms at high atomic densities on the pressure of the system were analyzed. It was found that the pressure in metals predominantly depends on the interaction forces between atoms at high atomic densities. In addition, expressions for melting pressure as a function of temperature have been obtained by fitting the simulation results.

Molecular Dynamics Study of Proton and Water Transport in Nafion Membrane

2013 ◽  
Author(s):  
Takuya Mabuchi ◽  
Takashi Tokumasu
Keyword(s):  
Experimental Data ◽  
Molecular Dynamics ◽  
Diffusion Coefficient ◽  
Water Clusters ◽  
Nafion Membrane ◽  
Water Molecules ◽  
Static Structure ◽  
Hydration Level ◽  
Hydronium Ions ◽  
Structure Factors

Polymer electrolyte fuel cells (PEFCs) are highly expected as a next-generation power supply system due to the purity of its exhaust gas, its high power density and high efficiency. The polymer electrolyte membrane is a critical component for the performance of the PEFCs and it is important to understand the nanostructure in the membrane to enhance proton transport. We have performed an atomistic analysis of the vehicular transport of hydronium ions and water molecules in the nanostructure of hydrated Nafion membrane by systematically changing the hydration level which provides insights into a connection between the nanoscopic and mesoscopic structure of ion clusters and the dynamics of hydronium ions and water molecules in the hydrated Nafion membrane. In this study, classical molecular dynamics simulations are implemented using a model of Nafion membrane which is based on DREIDING force field and newly modified and validated by comparing the density, water diffusivity, and Nafion morphology with experimental data. The simulated final density after the annealing procedure agrees with experiment within 1.3 % for various water contents and the trends that density decreases with increasing hydration level are reproduced. In addition to determination of diffusion coefficients of solvent molecules as a function of hydration level (from λ = 1 up to λ = 18), we have also calculated radial distribution functions and static structure factors not only to clarify the structure of water molecules and hydronium ions around the first solvation shell of sulfonate groups but also to validate the mesoscopic periodic structure among water clusters. The diffusion coefficient of water molecules increases with increasing hydration level and is found to be in good agreement with experimental data. The diffusion coefficient of hydronium ions has showed that general trends in the experimental data are reproduced by the simulations although the classical models have the limitation of probing hydronium dynamics. The static structure factors of liquid molecules at low wave length provide insights into the periodic structure of the inter-water clusters. These results are consistent with the Gebel’s model based on small-angle X-ray scattering that considers the dry membrane to be made of isolated spherical ionic clusters of radius ∼7.5 Å that swell with increasing hydration.

scholarly journals Computer Simulation of Formation Energy and Migration Energy of Vacancies under High Strain in Cu

2004 ◽  
Vol 45 (3) ◽  
pp. 833-838 ◽  
Author(s):  
Koichi Sato ◽  
Toshimasa Yoshiie ◽  
Yuhki Satoh ◽  
Qiu Xu
Keyword(s):  
Computer Simulation ◽  
Formation Energy ◽  
High Strain ◽  
Migration Energy ◽  
And Migration

Role of point defects in self-diffusion along low-angle twist boundaries in fcc metals: A molecular dynamics study

2018 ◽  
Vol 03 (01n02) ◽  
pp. 1850001 ◽  
Author(s):  
G. M. Poletaev ◽  
I. V. Zorya ◽  
M. D. Starostenkov
Keyword(s):  
Molecular Dynamics ◽  
Grain Boundary ◽  
Point Defects ◽  
Binding Energies ◽  
Fcc Metals ◽  
Self Diffusion ◽  
Thermodynamic Equilibrium Condition ◽  
Dynamics Method ◽  
Twist Boundaries

The interaction of point defects with low-angle (100), (110) and (111) twist boundaries in fcc metals Ni, Cu, Al and role of the point defects in self-diffusion along considered boundaries were studied by the molecular dynamics method. The binding energies of point defects with low-angle twist boundaries were calculated. It was found that the point defects are mainly fixed in the nodes of grain-boundary screw dislocations network. It was shown that the introduced vacancies play an important role in diffusion along twist grain boundaries. The contribution of introduced interstitial atoms to grain-boundary diffusion under thermodynamic equilibrium condition is less by several orders of magnitude in comparison with the contribution of vacancies.

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