Molecular Dynamics Simulation of Radiation-Induced Amorphization of the Ordered Compound NiZr2

1992 ◽  
Vol 279 ◽  
Author(s):  
R. Devanathan ◽  
N. Q. Lami ◽  
P. R. Okamoto ◽  
M. Meshii
Keyword(s):  
Molecular Dynamics ◽  
Perfect Crystal ◽  
Dynamics Simulation ◽  
Embedded Atom ◽  
Chemical Disorder ◽  
Average Shear ◽  
Ordered Intermetallic ◽  
Radiation Induced ◽  
Diffraction Patterns ◽  
Dynamics Simulations

ABSTRACTWe have studied the electron irradiation-induced amorphization of the ordered intermetallic compound NizR2 by molecular dynamics simulations in conjunction with embedded-atom potentials. Randomly chosen Frenkel pairs and chemical disorder were introduced into the system in separate processes. In both cases, the energy and volume of the system rose above the corresponding levels of a quenched liquid and the calculated diffraction patterns indicated the occurence of a crystalline-to-amorphous transition. In addition, the average shear elastic constant fell to about 50% of its value in the perfect crystal and the system became elastically isotropie. These results indicate that NiZr2 can be amorphized by chemical disorder as well as Frenkel pairs and are in good agreement with experimental observations.

Molecular-Dynamics Study of the Amorphizatton of CuTi

1989 ◽  
Vol 157 ◽  
Author(s):  
Michael J. Sabochick ◽  
Nghi Q. Lam
Keyword(s):  
Molecular Dynamics ◽  
Pair Correlation ◽  
Embedded Atom Method ◽  
Interatomic Potentials ◽  
Embedded Atom ◽  
Atomic Displacements ◽  
Chemical Disorder ◽  
Radiation Induced ◽  
System Energy ◽  
Dynamics Simulations

ABSTRACTRadiation-induced amorphization of the crystalline compound CuTi was investigated by molecular-dynamics simulations using new interatomic potentials derived from the embedded-atom method. Two different approaches to amorphization were tried: one in which Cu and Ti atoms were randomly exchanged, and another in which Frenkel pairs were introduced at random. The potential energy, volume expansion and pair-correlation function were calculated as functions of chemical disorder and atomic displacements. The results indicate that, although both chemical disordering and point-defect introduction increase the system energy and volume, the presence of Frenkel pairs is essential to trigger the crystalline-to-amorphous transition.

Molecular Dynamics Simulation of Electron Irradiation-Induced Amortization of the Ordered Compound NiZr

1991 ◽  
Vol 235 ◽  
Author(s):  
R. Devanathan ◽  
N. Q. Lam ◽  
M. J. Sabochick ◽  
P. R. Okamoto ◽  
M. Meshh
Keyword(s):  
Molecular Dynamics ◽  
Molecular Dynamics Simulation ◽  
Intermetallic Compound ◽  
Elastic Constant ◽  
Elastic Constants ◽  
Electron Irradiation ◽  
Dynamics Simulation ◽  
Embedded Atom ◽  
Average Shear ◽  
Ordered Intermetallic

ABSTRACTWe present the results of a molecular dynamics simulation of the crystalline-to-amorphous transformation in the ordered intermetallic compound NiZr, using embedded-atom potentials. It is found that NiZr can be amorphized by random atom exchanges as well as by the introduction of Frenkel pairs. In both cases, the shear elastic constants C44 and C decreased drastically and eventually became equal. The average shear elastic constant fell to about 40% of its original value. These results are in general agreement with experimental observations.

Molecular Dynamics Simulation of Sputtering with Mmany-Body Interactions

1988 ◽  
Vol 100 ◽  
Author(s):  
Davy Y. Lo ◽  
Tom A. Tombrello ◽  
Mark H. Shapiro ◽  
Don E. Harrison
Keyword(s):  
Molecular Dynamics ◽  
Molecular Dynamics Simulation ◽  
Single Crystal ◽  
Low Energy ◽  
Dynamics Simulation ◽  
Embedded Atom Method ◽  
Many Body ◽  
Embedded Atom ◽  
Dynamics Simulations ◽  
Small Single Crystal

ABSTRACTMany-body forces obtained by the Embedded-Atom Method (EAM) [41 are incorporated into the description of low energy collisions and surface ejection processes in molecular dynamics simulations of sputtering from metal targets. Bombardments of small, single crystal Cu targets (400–500 atoms) in three different orientations ({100}, {110}, {111}) by 5 keV Ar+ ions have been simulated. The results are compared to simulations using purely pair-wise additive interactions. Significant differences in the spectra of ejected atoms are found.

Characterization of Interatomic Potentials by a Calculation of Defect Energy

1997 ◽  
Vol 491 ◽  
Author(s):  
Y. Kogure ◽  
M. Doyama
Keyword(s):  
Molecular Dynamics ◽  
Noble Metals ◽  
Dynamics Simulation ◽  
Interatomic Potentials ◽  
Third Order ◽  
Jones Potential ◽  
Embedded Atom ◽  
Third Order Elastic Constants ◽  
Dynamics Simulations

ABSTRACTPotential functions used in molecular dynamics simulations for metals are characterized through a calculation of the third-order elastic constants, the Gruneisen parameters, and the molecular dynamics simulation of point defects. The Lennard-Jones potential and the embedded atom method potentials for noble metals (Cu, Ag, Au) are characterized by using a common program code.

Deducing density and strength of nanocrystalline Ta and diamond under extreme conditions from X-ray diffraction

2019 ◽  
Vol 26 (2) ◽  
pp. 413-421 ◽  
Author(s):  
Y. Y. Zhang ◽  
M. X. Tang ◽  
Y. Cai ◽  
J. C. E ◽  
S. N. Luo
Keyword(s):  
Shock Wave ◽  
Molecular Dynamics ◽  
Large Scale ◽  
Density Measurement ◽  
Dynamics Simulation ◽  
Extreme Conditions ◽  
X Ray Diffraction ◽  
X Ray ◽  
Diffraction Patterns ◽  
Dynamics Simulations

In situ X-ray diffraction with advanced X-ray sources offers unique opportunities for investigating materials properties under extreme conditions such as shock-wave loading. Here, Singh's theory for deducing high-pressure density and strength from two-dimensional (2D) diffraction patterns is rigorously examined with large-scale molecular dynamics simulations of isothermal compression and shock-wave compression. Two representative solids are explored: nanocrystalline Ta and diamond. Analysis of simulated 2D X-ray diffraction patterns is compared against direct molecular dynamics simulation results. Singh's method is highly accurate for density measurement (within 1%) and reasonable for strength measurement (within 10%), and can be used for such measurements on nanocrystalline and polycrystalline solids under extreme conditions (e.g. in the megabar regime).

Molecular Dynamics Simulations of Low Energy Displacement Cascades in the Ordered Compound CuTi

1991 ◽  
Vol 235 ◽  
Author(s):  
H. Zhu ◽  
N. Q. Lam ◽  
R. Devanathan ◽  
M. J. Sabochick
Keyword(s):  
Molecular Dynamics ◽  
Molecular Dynamics Simulations ◽  
Threshold Energy ◽  
Damage Function ◽  
Low Energy ◽  
Displacement Cascades ◽  
Embedded Atom ◽  
Ordered Intermetallic ◽  
Frenkel Defects ◽  
Dynamics Simulations

ABSTRACTThe properties of low-energy (≤500 eV) displacement cascades in the ordered intermetallic compound CuTi have been investigated by molecular dynamics simulations in conjunction with recently-developed embedded-atom potentials. Various aspects of the time evolution of cascades produced by Cu and Ti primary knock-on atoms have been considered, including the dynamics of Frenkel-pair production, generation of ‘pure’ replacements and anti-site defects, and the anisotropy of the threshold energy for displacement. The spatial distributions of Frenkel defects and the damage function have been analyzed, based on information obtained from various simulated events corresponding to different recoil directions.

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.

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.

Molecular Dynamics Simulation Study of Lecithin Inhibiting Hydrate-Dissociation

2017 ◽  
Vol 890 ◽  
pp. 252-259
Author(s):  
Le Wang ◽  
Guan Cheng Jiang ◽  
Xin Lin ◽  
Xian Min Zhang ◽  
Qi Hui Jiang
Keyword(s):  
Molecular Dynamics ◽  
Water Movement ◽  
Simulation Analysis ◽  
Mass Density ◽  
Dynamics Simulation ◽  
Dissociation Process ◽  
Hydrate Dissociation ◽  
Hydrocarbon Chains ◽  
Dynamics Simulations ◽  
Mass Density Profile

Molecular dynamics simulations are used to study the dissociation inhibiting mechanism of lecithin for structure I hydrates. Adsorption characteristics of lecithin and PVP (poly (N-vinylpyrrolidine)) on the hydrate surfaces were performed in the NVT ensemble at temperatures of 277K and the hydrate dissociation process were simulated in the NPT ensemble at same temperature. The results show that hydrate surfaces with lecithin is more stable than the ones with PVP for the lower potential energy. The conformation of lecithin changes constantly after the balanced state is reached while the PVP molecular dose not. Lecithin molecule has interaction with lecithin nearby and hydrocarbon-chains of lecithin molecules will form a network to prevent the diffusion of water and methane molecules, which will narrow the available space for hydrate methane and water movement. Compared with PVP-hydrate simulation, analysis results (snapshots and mass density profile) of the dissociation simulations show that lecithin-hydrate dissociates more slowly.

Molecular Dynamics Simulations of High Energy Cascades in Iron

1994 ◽  
Vol 373 ◽  
Author(s):  
Roger E. Stoller
Keyword(s):  
Molecular Dynamics ◽  
Three Dimensional ◽  
High Energy ◽  
Dynamics Simulation ◽  
Method Of Molecular Dynamics ◽  
Energy Cascades ◽  
Iron Based ◽  
The Many ◽  
Property Changes ◽  
Dynamics Simulations

AbstractA series of high-energy, up to 20 keV, displacement cascades in iron have been investigated for times up to 200 ps at 100 K using the method of molecular dynamics simulation. Thesimulations were carried out using the MOLDY code and a modified version of the many-bodyinteratomic potential developed by Finnis and Sinclair. The paper focuses on those results obtained at the highest energies, 10 and 20 keV. The results indicate that the fraction of the Frenkel pairs surviving in-cascade recombination remains fairly high in iron and that the fraction of the surviving point defects that cluster is lower than in materials such as copper. In particular, vacancy clustering appears to be inhibited in iron. Some of the interstitial clusters were observed to exhibit an unexpectedly complex, three-dimensional morphology. The observations are discussed in terms of their relevance to microstructural evolution and mechanical property changes in irradiated iron-based alloys.

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