Structural Trends in Amorphous Carbon

1997 ◽  
Vol 498 ◽  
Author(s):  
C. Z. Wang ◽  
K. M. Ho
Keyword(s):  
Molecular Dynamics ◽  
Amorphous Carbon ◽  
Relative Concentration ◽  
Tight Binding ◽  
Binding Potential ◽  
Low Density ◽  
Liquid Carbon ◽  
Wide Range ◽  
Simulation Results ◽  
Dynamics Simulations

ABSTRACTAmorphous carbon (a-C) structures over a wide range of densities are generated by tight-binding molecular dynamics simulations using the recently developed environment-dependent carbon tight-binding potential. Our simulation results show that the relative concentration of the sp2 and sp3 bondings in the a-C samples changes systematically with the density of the samples. The a-C networks obtained by quenching the low density liquids consist of mostly three-fold coordinated atoms while the diamond-like tetrahedral a-C can be generated by quenching the high density (about 3.0g/cm3) liquid carbon.

Tight-Binding Molecular Dynamics Study of Liquid and Amorphous Carbon

1992 ◽  
Vol 291 ◽  
Author(s):  
C. Z. Wang ◽  
K. M. Ho ◽  
C. T. Chan
Keyword(s):  
Experimental Data ◽  
Molecular Dynamics ◽  
Ab Initio ◽  
Molecular Dynamics Simulations ◽  
Amorphous Carbon ◽  
Simulation Study ◽  
Tight Binding ◽  
Sufficient Accuracy ◽  
Complex Carbon ◽  
Dynamics Simulations

ABSTRACTTight-binding molecular-dynamics simulations are performed to study the structure of liquid and amorphous carbon. Comparisons of our results with ab initiomolecular dynamics (Car-Parrinello) results and experimental data show that the scheme has sufficient accuracy and efficiency for realistic simulation study of the structural properties of complex carbon systems.

scholarly journals Characterization of three phases of liquid carbon by tight-binding molecular dynamics simulations

2020 ◽  
Vol 22 (26) ◽  
pp. 14630-14636
Author(s):  
Rong Cheng ◽  
Wen-Cai Lu ◽  
K. M. Ho ◽  
C. Z. Wang
Keyword(s):  
Molecular Dynamics ◽  
Molecular Dynamics Simulations ◽  
Tight Binding ◽  
Liquid Carbon ◽  
Structures And Properties ◽  
Dynamics Simulations ◽  
Density Regime ◽  
Three Phases

We have performed tight-binding molecular dynamics simulations to study the structures and properties of liquid carbon with the density ranging from 1.4 to 3.5 g cm−3, and identified three liquid carbon phases at different density regime.

scholarly journals Localized electronic and vibrational states in amorphous diamond

2021 ◽  
Vol 23 (8) ◽  
pp. 4835-4840
Author(s):  
Rong Cheng ◽  
Wen-Cai Lu ◽  
K. M. Ho ◽  
C. Z. Wang
Keyword(s):  
Molecular Dynamics ◽  
Molecular Dynamics Simulations ◽  
Tight Binding ◽  
Vibrational Properties ◽  
Vibrational States ◽  
Liquid Carbon ◽  
Amorphous Sample ◽  
Dynamics Simulations

Amorphous diamond structures with more than 97% of sp3 bonding fraction are generated by quenching liquid carbon using tight-binding molecular-dynamics simulations. The electronic and vibrational properties of the amorphous sample are investigated.

Large-Scale Molecular Dynamics Simulations of Interstitial Defect Diffusion in Silicon

2002 ◽  
Vol 731 ◽  
Author(s):  
David A. Richie ◽  
Jeongnim Kim ◽  
Richard Hennig ◽  
Kaden Hazzard ◽  
Steve Barr ◽  
...  
Keyword(s):  
Molecular Dynamics ◽  
Large Scale ◽  
Materials Science ◽  
Tight Binding ◽  
Md Simulations ◽  
Binding Potential ◽  
Interstitial Defect ◽  
Long Time ◽  
Computational Materials ◽  
Dynamics Simulations

AbstractThe simulation of defect dynamics and evolution is a technologicaly relevant challenge for computational materials science. The diffusion of small defects in silicon unfolds as a sequence of structural transitions. The relative infrequency of transition events requires simulation over extremely long time scales. We simulate the diffusion of small interstitial clusters (I1, I2, I3) for a range of temperatures using large-scale molecular dynamics (MD) simulations with a realistic tight-binding potential. A total of 0.25 μ sec of simulation time is accumulated for the study. A novel real-time multiresolution analysis (RTMRA) technique extracts stable structures directly from the dynamics without structural relaxation. The discovered structures are relaxed to confirm their stability.

ATOMISTIC SIMULATION OF LASER ABLATION OF DIAMOND AND SILICON (111) SURFACE

1999 ◽  
Vol 06 (06) ◽  
pp. 1025-1030 ◽  
Author(s):  
C. Z. WANG ◽  
K. M. HO
Keyword(s):  
Molecular Dynamics ◽  
Laser Ablation ◽  
Lattice Dynamics ◽  
Atomistic Simulation ◽  
Structural Changes ◽  
Tight Binding ◽  
Femtosecond Laser Ablation ◽  
Ultrafast Laser ◽  
Simulation Results ◽  
Dynamics Simulations

Tight-binding molecular dynamics simulations are performed to study femtosecond-laser ablation of diamond and silicon (111) surface. The simulation results show that under intense ultrafast laser ablation the diamond (111) surface graphitizes while the silicon (111) surface melts spontaneously. All structural changes occur within a few hundred femtoseconds, which is much shorter than the typical lattice dynamics time scale, in consistent with experimental observations.

scholarly journals Finite-Temperature Single Molecule Vibrational Dynamics from Combined Density Functional Tight Binding Extended Lagrangian Dynamics Simulations and Time Series Analysis

2020 ◽  
Vol 20 (6) ◽  
pp. 201-212
Author(s):  
Bojana Koteska ◽  
Anastas Mishev ◽  
Ljupco Pejov
Keyword(s):  
Molecular Dynamics ◽  
Time Series ◽  
Single Molecule ◽  
Density Functional ◽  
Tight Binding ◽  
Range Data ◽  
Computationally Efficient ◽  
Vibrational Dynamics ◽  
Wide Range ◽  
Dynamics Simulations

AbstractCombining a computationally efficient and affordable molecular dynamics approach, based on atom-centered density matrix propagation scheme, with the density functional tight binding semiempirical quantum mechanics, we study the vibrational dynamics of a single molecule at series of finite temperatures, spanning quite wide range. Data generated by molecular dynamics simulations are further analyzed and processed using time series analytic methods, based on correlation functions formalism, leading to both vibrational density of states spectra and infrared absorption spectra at finite temperatures. The temperature-induced dynamics in structural intramolecular parameters is correlated to the observed changes in the spectral regions relevant to molecular detection. In particular, we consider a case when an intramolecular X-H stretching vibrational states are notably dependent on the intramolecular torsional degree of freedom, the dynamics of which is, on the other hand, strongly temperature-dependent.

A Molecular Dynamics Study of the Terminal Zr(Ni) Solid Solutions

1995 ◽  
Vol 400 ◽  
Author(s):  
F. Cleri ◽  
G. Mazzone ◽  
V. Rosato
Keyword(s):  
Molecular Dynamics ◽  
Phase Diagram ◽  
Solid Solutions ◽  
Tight Binding ◽  
Solid State Reactions ◽  
Binding Potential ◽  
Terminal Portion ◽  
Many Body ◽  
Empirical Phase Diagram ◽  
Dynamics Simulations

AbstractThe Zr terminal portion of the Zr-Ni phase diagram has been evaluated by means of a many-body tight-binding potential. The internal energy curves of the Zr(Ni) solid solutions at T=300 K have been calculated by Molecular Dynamics simulations. These curves exhibit positive values, contrary to former empirical phase diagram calculations. Implications of these results relevant to the problem of amorphization in metallic systems by solid-state reactions are discussed.

On the Use of the Reverse Monte Carlo Technique to Generate Amorphous Carbon Structures

1998 ◽  
Vol 09 (07) ◽  
pp. 917-926 ◽  
Author(s):  
Vittorio Rosato ◽  
Juan C. Lascovich ◽  
Antonino Santoni ◽  
Luciano Colombo
Keyword(s):  
Molecular Dynamics ◽  
Monte Carlo ◽  
Amorphous Carbon ◽  
Radial Distribution ◽  
Tight Binding ◽  
Distribution Functions ◽  
Dynamics Simulation ◽  
Reverse Monte Carlo ◽  
Atomic Structures ◽  
Dynamics Simulations

The reverse Monte Carlo (RMC) technique has been used to generate atomic structures of amorphous carbon based on the radial distribution functions and the fraction of differently coordinated sites measured on experimental samples. The resulting structures have been subsequently relaxed via a Tight Binding Molecular Dynamics simulation (TBMD). The radial distribution function, the energy and the fraction of 2-, 3- and 4-fold coordinated sites, evaluated on the relaxed structures, have been compared to those calculated for atomic systems generated on the basis of the "conventional" numerical melt-quench technique. We thus suggest the possibility of using RMC modeling as a useful and convenient tool for generating amorphous structures to be used as initial configurations in Molecular Dynamics simulations.

Interpretation of the Infrared Spectra of β-FeSi2 by Molecular Dynamics Simulations

1995 ◽  
Vol 402 ◽  
Author(s):  
Leo Miglio ◽  
Valeria Meregalli
Keyword(s):  
Molecular Dynamics ◽  
Molecular Dynamics Simulations ◽  
Infrared Spectra ◽  
Vibrational Spectra ◽  
Tight Binding ◽  
Binding Potential ◽  
Anisotropic Behaviour ◽  
Dynamics Simulations

AbstractWe report the vibrational spectra of β-FeSi2 calculated by molecular dynamics simulations with a tight binding potential and provide a quantitative confirmation of the anisotropic behaviour found by new Infrared (IR) measurements for small monocrystals This analysis allows for the interpretation of more complex IR results previously found for epitaxial samples.

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