A Tight-Binding Molecular Dynamics Simulation of the Melting and Solidification of Silicon

1992 ◽  
Vol 291 ◽  
Author(s):  
Andrew Horsfield ◽  
Paulette Clancy
Keyword(s):  
Molecular Dynamics ◽  
Electrical Conductivity ◽  
Crystalline Silicon ◽  
Pair Correlation ◽  
Tight Binding ◽  
Diffusion Constant ◽  
Low Frequency ◽  
Dynamics Simulation ◽  
Three Body ◽  
Body Energy

ABSTRACTThe melting of crystalline silicon and the cooling of liquid silicon are investigated using Molecular Dynamics. Both the Stillinger-Weber (SW) potential and the Tight-Binding Bond Model are used to calculate the forces. The electrical properties are investigated using an empirical pseudopotential method with a plane wave basis. The melting point of the solid is found to be about 2300K. The dependency of this temperature with cell size is investigated. On cooling, there are changes in some of the properties of the liquid: the energy per particle decreases, the diffusion constant decreases, and the low frequency electrical conductivity decreases slightly as the temperature decreases. Between 1180K and 980K the liquid undergoes a transition to a glassy phase. There are large changes in the pair correlation function, the SW three-body energy distribution, the diffusion constant, the density of electron single particle states and the electrical conductivity. All of these changes are consistent with increased tetrahedral bonding.

Defect Induced Amortization in Silicon: A Tight Binding Molecular Dynamics Simulation

1993 ◽  
Vol 321 ◽  
Author(s):  
D. Maric ◽  
L. Colombo
Keyword(s):  
Molecular Dynamics ◽  
Electronic Properties ◽  
Structural Properties ◽  
Crystalline Silicon ◽  
Ion Beam ◽  
Tight Binding ◽  
Dynamics Simulation ◽  
Rapid Quench ◽  
Amorphous Network ◽  
Different Temperatures

ABSTRACTWe present an investigation on the amorphization process of crystalline silicon induced by ion beam bombardment by simulating the insertion of self-interstitials at different temperatures. The simulation is carried out by tight-binding molecular dynamics which allows for a detailed characterization of the chemical bonding and electronic properties of the irradiated samples. The irradiation process consists of two steps: (i) insertion of defects at a constant rate; (ii) annealing of the sample and observation of its structural properties. Thanks to the large size of the simulation cell (up to 276 atoms) we can characterize the amorphous network both on the short-range and Medium-range length scale. Electronic properties are investigated as well and their evolution is monitored during the insertion process. Finally, we present a thorough comparison of the structural properties of the irradiated sample with amorphous silicon as obtained by rapid quench from the Melt.

Defect Induced Amortization in Silicon: A Tight Binding Molecular Dynamics Simulation

1993 ◽  
Vol 316 ◽  
Author(s):  
D. Maric ◽  
L. Colombo
Keyword(s):  
Molecular Dynamics ◽  
Electronic Properties ◽  
Structural Properties ◽  
Crystalline Silicon ◽  
Ion Beam ◽  
Tight Binding ◽  
Dynamics Simulation ◽  
Rapid Quench ◽  
Amorphous Network ◽  
Different Temperatures

ABSTRACTWe present an investigation on the amorphization process of crystalline silicon induced by ion beam bombardment by simulating the insertion of self-interstitials at different temperatures. The simulation is carried out by tight-binding molecular dynamics which allows for a detailed characterization of the chemical bonding and electronic properties of the irradiated samples. The irradiation process consists of two steps: (i) insertion of defects at a constant rate; (ii) annealing of the sample and observation of its structural properties. Thanks to the large size of the simulation cell (up to 276 atoms) we can characterize the amorphous network both on the short-range and medium-range length scale. Electronic properties are investigated as well and their evolution is monitored during the insertion process. Finally, we present a thorough comparison of the structural properties of the irradiated sample with amorphous silicon as obtained by rapid quench from the melt.

Molecular Dynamics Simulation of Mass and Charge Transport in Superionic Conductors, and Structural Correlations in Chalcogenide Glasses

1988 ◽  
Vol 135 ◽  
Author(s):  
P. Vashishta ◽  
José P. Rino ◽  
Rajiv K. Kalia
Keyword(s):  
Molecular Dynamics ◽  
Charge Transport ◽  
Chalcogenide Glasses ◽  
Pair Correlation ◽  
Diffusion Constant ◽  
Dynamics Simulation ◽  
Superionic Conductors ◽  
Static Structure Factor ◽  
Static Structure ◽  
Good Agreement

AbstractStructural properties, single-particle dynamics, and the charge transport are studied in superionic conductor Ag2Se using the molecular dynamics (MD) technique. The calculations are based on a model of interionic potentials in which ions interact through Coulomb interaction, steric repulsion and charge-dipole interaction due to the large electronic polarizability of the selenium ions. Structural and dynamics correlations are studied at five temperatures in the superionic phase. Among the structural correlations the results are presented for partial pair correlation function, coordination numbers, bond angle distributions and wave-vector dependence of the Bragg intensities. Detailed comparison with neutron and x-ray single crystal diffraction experiments. The calculated temperature dependence of the self-diffusion constant of silver is in good agreement with the tracer diffusion measurements. The spectra of velocity autocorrelation functions and the frequency dependent ionic conductivity are calculated. The Haven's ratio is also in good agreement with experiments.Effective interatomic potentials consisting of two-body (steric effect, charge transfer and charge-dipole interactions) and three-body covalent forces are proposed for GeSe2. Using these interaction potentials in MD simulations, the nature of short-range and medium-range order is investigated in glassy and molten GeSe2. All the features in the static structure factor, S(q), including the first sharp diffraction peak (FSDP), are in good agreement with experiments. The FSDP arises from Ge-Ge and Ge-Se correlations between 4-8Å, and the anomalous decrease in its height on cooling is due to frustration enhanced by the increased density.

scholarly journals Tight-Binding Molecular Dynamics Simulations on Point Defects Diffusion and Interactions in Crystalline Silicon

1995 ◽  
Vol 396 ◽  
Author(s):  
M. tang ◽  
L. colombo ◽  
T. Diaz De La Rubia
Keyword(s):  
Molecular Dynamics ◽  
Molecular Dynamics Simulations ◽  
Point Defects ◽  
Crystalline Silicon ◽  
Tight Binding ◽  
Diffusion Path ◽  
Binding Energies ◽  
Defect Clusters ◽  
Dynamics Simulations

AbstractTight-binding molecular dynamics (TBMD) simulations are performed (i) to evaluate the formation and binding energies of point defects and defect clusters, (ii) to compute the diffusivity of self-interstitial and vacancy in crystalline silicon, and (iii) to characterize the diffusion path and mechanism at the atomistic level. In addition, the interaction between individual defects and their clustering is investigated.

Magnetized property effect of a non-aqueous solvent upon complex formation between kryptofix 22DD with lanthanum(iii) cation: experimental aspects and molecular dynamics simulation

RSC Advances ◽  
2016 ◽  
Vol 6 (11) ◽  
pp. 9096-9105 ◽  
Author(s):  
Gholam Hossien Rounaghi ◽  
Mostafa Gholizadeh ◽  
Fatemeh Moosavi ◽  
Iman Razavipanah ◽  
Hossein Azizi-Toupkanloo ◽  
...  
Keyword(s):  
Molecular Dynamics ◽  
Correlation Function ◽  
Molecular Dynamics Simulation ◽  
Pair Correlation ◽  
Molar Conductance ◽  
Methanol Solution ◽  
Dynamics Simulation ◽  
Aqueous Solvent ◽  
Different Temperatures ◽  
Kryptofix 22Dd

The variation of molar conductance versus mole ratio for (kryptofix 22DD·La)3+ complex in methanol solution at different temperatures is in accordance with the variation of pair correlation function of oxygen atoms.

Bayesian active learning of interatomic force field for molecular dynamics simulation of Pt/Ag(111)

2021 ◽  
Author(s):  
Kai Xu ◽  
Lei Yan ◽  
Bingran You
Keyword(s):  
Molecular Dynamics ◽  
Active Learning ◽  
Force Field ◽  
Density Functional ◽  
Process Model ◽  
Large Scale ◽  
Computational Cost ◽  
Dynamics Simulation ◽  
Potential Energy Landscape ◽  
Three Body

Force field is a central requirement in molecular dynamics (MD) simulation for accurate description of the potential energy landscape and the time evolution of individual atomic motions. Most energy models are limited by a fundamental tradeoff between accuracy and speed. Although ab initio MD based on density functional theory (DFT) has high accuracy, its high computational cost prevents its use for large-scale and long-timescale simulations. Here, we use Bayesian active learning to construct a Gaussian process model of interatomic forces to describe Pt deposited on Ag(111). An accurate model is obtained within one day of wall time after selecting only 126 atomic environments based on two- and three-body interactions, providing mean absolute errors of 52 and 142 meV/Å for Ag and Pt, respectively. Our work highlights automated and minimalistic training of machine-learning force fields with high fidelity to DFT, which would enable large-scale and long-timescale simulations of alloy surfaces at first-principles accuracy.

Momentum Removal to Obtain the Position-Dependent Diffusion Constant in Constrained Molecular Dynamics Simulation

2021 ◽  
Author(s):  
Kazushi Fujimoto ◽  
Tetsuro Nagai ◽  
Tsuyoshi Yamaguchi
Keyword(s):  
Molecular Dynamics ◽  
Diffusion Coefficient ◽  
Mass Velocity ◽  
Center Of Mass ◽  
Heterogeneous Systems ◽  
Diffusion Constant ◽  
Dynamics Simulation ◽  
Coulombic Interaction ◽  
Ewald Method ◽  
Theoretical Predictions

<div>The position-dependent diffusion coefficient along with free energy profile are important parameters needed to study mass transport in heterogeneous systems such as biological and polymer membranes, and molecular dynamics (MD) calculation is a popular tool to obtain them. Among many methodologies, the Marrink-Berendsen (MB) method is often employed to calculate the position-dependent diffusion coefficient, in which the autocorrelation function of the force on a fixed molecule is related to the friction on the molecule. However, the diffusion coefficient is shown to be affected by the period of the removal of the center-of-mass velocity, which is necessary when performing MD calculations using the Ewald method for Coulombic interaction. We have clarified theoretically in this study how this operation affects the diffusion coefficient calculated by the MB method, and the theoretical predictions are proven by MD calculations. Therefore, we succeeded in providing guidance on how to select an appropriate the period of the removal of the center-of-mass velocity in estimating the position-dependent diffusion coefficient by the MB method. This guideline is applicable also to the Woolf-Roux method.</div>

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