Direct Molecular Dynamics Simulations of Diffusion Mechanisms in NiAl

2000 ◽  
Vol 646 ◽  
Author(s):  
D. Farkas ◽  
B. Soulé de Bas
Keyword(s):  
Molecular Dynamics ◽  
High Temperature ◽  
Molecular Dynamics Simulations ◽  
Sequential Analysis ◽  
Nearest Neighbor ◽  
Interatomic Potential ◽  
Embedded Atom ◽  
Diffusion Mechanisms ◽  
Dynamics Simulations ◽  
Potential Diffusion

ABSTRACTMolecular dynamics simulations of the diffusion process in ordered B2 NiAl at high temperature were performed using an embedded atom interatomic potential. Diffusion occurs through a variety of cyclic mechanisms that accomplish the motion of the vacancy through nearest neighbor jumps restoring order to the alloy at the end of the cycle. The traditionally postulated 6-jump cycle is only one of the various cycles observed and some of these are quite complex. A detailed sequential analysis of the observed 6-jump cycles was performed and the results are analyzed in terms of the activation energies for individual jumps calculated using molecular statics simulations.

scholarly journals Reactive molecular dynamics simulation of the high-temperature pyrolysis of 2,2′,2′′,4,4′,4′′,6,6′,6′′-nonanitro-1,1′:3′,1′′-terphenyl (NONA)

RSC Advances ◽  
2020 ◽  
Vol 10 (9) ◽  
pp. 5507-5515
Author(s):  
Liang Song ◽  
Feng-Qi Zhao ◽  
Si-Yu Xu ◽  
Xue-Hai Ju
Keyword(s):  
Molecular Dynamics ◽  
High Temperature ◽  
Molecular Dynamics Simulation ◽  
Molecular Dynamics Simulations ◽  
Dynamics Simulation ◽  
Reactive Molecular Dynamics ◽  
Ring Compounds ◽  
Fused Ring ◽  
Dynamics Simulations

The bimolecular and fused ring compounds are found in the high-temperature pyrolysis of NONA using ReaxFF molecular dynamics simulations.

scholarly journals Development of a New Sr-O Parameterization to Describe the Influence of SrO on Iron-Phosphate Glass Structural Properties Using Molecular Dynamics Simulations

Materials ◽  
2021 ◽  
Vol 14 (15) ◽  
pp. 4326
Author(s):  
Pawel Goj ◽  
Aleksandra Wajda ◽  
Pawel Stoch
Keyword(s):  
Molecular Dynamics ◽  
Molecular Dynamics Simulations ◽  
Interatomic Potential ◽  
Glass Structure ◽  
Ion Pairs ◽  
Glass Network ◽  
Iron Phosphate ◽  
Phosphate Glasses ◽  
Potential Applications ◽  
Dynamics Simulations

Iron-phosphate glasses, due to their properties, have many potential applications. One of the most promising seems to be nuclear waste immobilization. Radioactive 90Sr isotope is the main short-lived product of fission and, due to its high solubility, it can enter groundwater and pose a threat to the environment. On the other hand, Sr is an important element in hard tissue metabolic processes, and phosphate glasses containing Sr are considered bioactive. This study investigated the effect of SrO addition on a glass structure of nominal 30Fe2O3-70P2O5 chemical composition using classical molecular dynamics simulations. To describe the interaction between Sr-O ion pairs, new interatomic potential parameters of the Buckingham-type were developed and tested for crystalline compounds. The short-range structure of the simulated glasses is presented and is in agreement with previous experimental and theoretical studies. The simulations showed that an increase in SrO content in the glass led to phosphate network depolymerization. Analysis demonstrated that the non-network oxygen did not take part in the phosphate network depolymerization. Furthermore, strontium aggregation in the glass structure was observed to lead to the non-homogeneity of the glass network. It was demonstrated that Sr ions prefer to locate near to Fe(II), which may induce crystallization of strontium phosphates with divalent iron.

scholarly journals First-Principles-Based Interatomic Potential for SI and Its Thermal Conductivity

2011 ◽  
Author(s):  
Keivan Esfarjani ◽  
Gang Chen ◽  
Asegun Henry
Keyword(s):  
Thermal Conductivity ◽  
Molecular Dynamics ◽  
Thermal Properties ◽  
Force Field ◽  
Molecular Dynamics Simulations ◽  
First Principles ◽  
Density Functional ◽  
Interatomic Potential ◽  
Force Constants ◽  
Dynamics Simulations

Based on first-principles density-functional calculations, we have developed and tested a force-field for silicon, which can be used for molecular dynamics simulations and the calculation of its thermal properties. This force field uses the exact Taylor expansion of the total energy about the equilibrium positions up to 4th order. In this sense, it becomes systematically exact for small enough displacements, and can reproduce the thermodynamic properties of Si with high fidelity. Having the harmonic force constants, one can easily calculate the phonon spectrum of this system. The cubic force constants, on the other hand, will allow us to compute phonon lifetimes and scattering rates. Results on equilibrium Green-Kubo molecular dynamics simulations of thermal conductivity as well as an alternative calculation of the latter based on the relaxation-time approximation will be reported. The accuracy and ease of computation of the lattice thermal conductivity using these methods will be compared. This approach paves the way for the construction of accurate bulk interatomic potentials database, from which lattice dynamics and thermal properties can be calculated and used in larger scale simulation methods such as Monte Carlo.

Angular dependent interatomic potential for Ti-V system for molecular dynamics simulations

2020 ◽  
Author(s):  
Andrey I. Kartamyshev ◽  
Alexey Gennadievich Lipnitskii ◽  
Anton Boev ◽  
Ivan Nelasov ◽  
Vyacheslav N. Maksimenko ◽  
...  
Keyword(s):  
Molecular Dynamics ◽  
Molecular Dynamics Simulations ◽  
Interatomic Potential ◽  
Dynamics Simulations

An Atomistic Study of Hydrogen Effects on the Fracture of Tilt Boundaries in Nickel.

1991 ◽  
Vol 238 ◽  
Author(s):  
N. R. Moody ◽  
S. M. Foiles
Keyword(s):  
Molecular Dynamics ◽  
Molecular Dynamics Simulations ◽  
Site Occupancy ◽  
Boundary Structure ◽  
Trap Site ◽  
Embedded Atom ◽  
Defect Sites ◽  
Tilt Boundaries ◽  
Temperature Exposure ◽  
Dynamics Simulations

ABSTRACTIn this study, molecular dynamics simulations were used to fracture Σ9 tilt boundaries in nickel lattices containing a range of trap site hydrogen concentrations. These lattices were created in a previous study using Monte Carlo simulations and the Embedded Atom Method to duplicate room temperature exposure to a hydrogen environment. The molecular dynamics simulations were run at absolute zero to immobilize the hydrogen distributions for determination of trap site occupancy effects on grain boundary fracture. In all lattices, fracture began by the breaking of bonds next to polyhedral defect sites that characterize the boundary structure followed by rapid failure of the remaining bonds. The effect of hydrogen was to lower the stress for fracture from 18 GPa to a lower limiting value of 8 GPa as the trap sites along the boundary plane filled. The simulations showed that the atoms at these sites were the only atoms involved in the fracture process. Within the constraints imposed on these calculations, the results of this study showed that the ‘inherent’ effect of hydrogen in the absence of plastic deformation is to reduce the cohesive force between atoms across the boundary.

Study on the structural transition of CoNi nanoclusters using molecular dynamics simulations

2018 ◽  
Vol 32 (11) ◽  
pp. 1850133
Author(s):  
J. H. Xia ◽  
Xue-Mei Gao
Keyword(s):  
Molecular Dynamics ◽  
Molecular Dynamics Simulations ◽  
Structural Transition ◽  
Correction Function ◽  
Embedded Atom Method ◽  
Embedded Atom ◽  
Analysis Technique ◽  
Dynamics Simulations ◽  
Embedded Atom Method Potential ◽  
Pair Analysis

In this work, the segregation and structural transitions of CoNi clusters, between 1500 and 300 K, have been investigated using molecular dynamics simulations with the embedded atom method potential. The radial distribution function was used to analyze the segregation during the cooling processes. It is found that Co atoms segregate to the inside and Ni atoms preferably to the surface during the cooling processes, the Co[Formula: see text]Ni[Formula: see text] cluster becomes a core–shell structure. We discuss the structural transition according to the pair-correction function and pair-analysis technique, and finally the liquid Co[Formula: see text]Ni[Formula: see text] crystallizes into the coexistence of hcp and fcc structure at 300 K. At the same time, it is found that the frozen structure of CoNi cluster is strongly related to the Co concentration.

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