Classical Molecular Dynamics Simulation of Structural and Dynamical Properties of II-VI and III-V Semiconductors

2006 ◽  
Vol 258-260 ◽  
pp. 522-530 ◽  
Author(s):  
José Pedro Rino ◽  
Paulo S. Branício ◽  
Denílson S. Borges
Keyword(s):  
Interaction Potential ◽  
Dipole Interaction ◽  
Van Der Waals Interactions ◽  
Dynamics Simulation ◽  
Static Structure Factor ◽  
Static Structure ◽  
Liquid Phases ◽  
Bond Stretching ◽  
Dynamical Properties ◽  
Three Body

An effective inter-atomic potential is proposed in order to describe structural and dynamical properties of II-VI and III-V semiconductors. The interaction potential consists of twoand three-body interactions. The two-body term takes into account steric repulsion, charge-induce dipole interaction due to the electronic polarizability of ions, Coulomb interaction due to charge transfer between ions, and dipole-dipole (van der Waals) interactions. The three-body term, which has a modified Stillinger-Weber form, describes bond-bending as well as bond-stretching effects. Here we report the fitting and the application of this interaction potential for InP in the crystalline phase and for CdTe in the crystalline and liquid phases. The structural correlations are discussed through pair distribution, coordination number and bond-angle functions. Vibrational density of states for InP and CdTe as well as the static structure factor for liquid CdTe are in very good agreement with experimental data.

Clustering and Extended Range Order in Binary Network Glasses

1995 ◽  
Vol 408 ◽  
Author(s):  
Dmitry Nekhayev ◽  
John Kieffer
Keyword(s):  
Network Structure ◽  
Pair Correlation ◽  
Range Order ◽  
Static Structure Factor ◽  
Static Structure ◽  
Silica Glasses ◽  
Dynamics Simulations ◽  
Binary Network ◽  
Three Body ◽  
Semi Empirical

AbstractThe clustering in alkali silica glasses (M2O) x (SiO2)1-x, where M is either Na or Rb, and x ranges between 0 and 0.4, was studied using molecular dynamics simulations. Computations were performed using a semi-empirical potential, including two- and three-body terms as well as dynamic partial charge transfer. Characterization of the structures was based on pair correlation functions, neutron static structure factor and ring statistics. Results have shown a much stronger tendency to cluster in case of Na than of Rb. The irregular arrangement of Na is evidenced by a decay pattern in the Na-Na pair correlation function, which can be associated with a fractal dimension. The clustering tendency can be attributed to the differences in the way the network structure is able to accommodate the introduction of modifying cations. As opposed to Rb, the smaller Na cation can fit on sites only slightly larger than is required for Si. This would distort the structure but hardly alter its topology. Rb on the other hand, requires larger interstices, which results in a reconstruction of the network and a significantly different intermediate range order. Na can achieve a similar influence on the network structure if they group in pairs.

Application of a New Three-Body Potential to Vitreous Silica and Sodium Silicate Glasses

1988 ◽  
Vol 141 ◽  
Author(s):  
B. P. Feuston ◽  
R. N. Newell ◽  
S. H. Garofalini
Keyword(s):  
Sodium Silicate ◽  
Silicate Glass ◽  
Md Simulations ◽  
Pair Interaction ◽  
Vitreous Silica ◽  
Static Structure Factor ◽  
Static Structure ◽  
Three Body ◽  
Body Potential ◽  
Good Agreement

AbstractAn empirical three-body potential, suitable for molecular dynamics (MD) simulations, has been developed to model the natural covalency of the Si-O bond in vitreous silica and silicate glass systems. Through the addition of a small directional-dependent three-body term to a previously used modified ionic pair interaction, a narrow distribution of tetrahedral angles and a low concentration of defects were obtained, in good agreement with experiment. The structure of bulk silica resulting from the MD technique also contained a larger average ring size, no edge-sharing tetrahedra, and a calculated static structure factor in good agreement with neutron diffraction results. The simulated sodium silicate glass was also largely improved over previous simulations using pair interactions alone. All silicon atoms were found to be exactly four coordinated while the number of non-bridging oxygen nearly equaled the number of sodium ions present with a reasonable distribution of Qi species.

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.

Molecular-Dynamics Simulation of Thin-Film Growth

1986 ◽  
Vol 77 ◽  
Author(s):  
Matthias Schneider ◽  
Ivan K. Schuller ◽  
A. Rahman
Keyword(s):  
Thin Films ◽  
Molecular Dynamics ◽  
Epitaxial Growth ◽  
Interaction Potential ◽  
Binary Systems ◽  
Film Growth ◽  
Equations Of Motion ◽  
Dynamics Simulation ◽  
Three Body ◽  
Body Potential

ABSTRACTThe epitaxial growth of thin films has been studied by molecular-dynamics computer simulation. In these simulations atoms are projected towards a temperature-controlled substrate, and the equations of motion of all atoms are solved for a given interaction potential. The calculations give insight into the microscopic structure of thin films, the dynamics of the adsorption process, and they help answer the way in which substrate temperature, form of the substrate, flux of impinging atoms, and form of the interaction potential, affect epitaxial growth. Simulations were performed for monatomic and binary systems with spherically symmetric atomic interactions, and for systems in which the atoms are interacting via a three-body potential to simulate the epitaxial growth of silicon.

The static structure factor S(Q) of partially deuterated ethyl- and hexylmethacrylate polymers

2000 ◽  
Vol 276-278 ◽  
pp. 369-370 ◽  
Author(s):  
G. Meier ◽  
U. Pawelzik ◽  
W. Schweika ◽  
W. Kockelmann
Keyword(s):  
Structure Factor ◽  
Static Structure Factor ◽  
Static Structure

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.

Molecular Dynamics Simulation of the Buckling Behavior of Boron Nitride Nanotubes under Uniaxial Compressive Loading

2010 ◽  
Vol 297-301 ◽  
pp. 984-989 ◽  
Author(s):  
S. Ebrahimi-Nejad ◽  
Ali Shokuhfar ◽  
A. Zare-Shahabadi
Keyword(s):  
Boron Nitride ◽  
Compressive Loading ◽  
Pair Potential ◽  
Md Simulations ◽  
Boron Nitride Nanotubes ◽  
Dynamics Simulation ◽  
Buckling Loads ◽  
Buckling Behavior ◽  
Bond Stretching ◽  
Different Diameters

Boron Nitride nanotubes (BNNTs) together with carbon nanotubes (CNTs) have attracted the wide attention of the scientific community and have been considered as promising materials due to their unique structural and physical properties. In this paper, the behavior of BNNTs of different diameters under compressive loading has been studied through molecular dynamic (MD) simulations. We have used a Lennard-Jones pair potential to characterize the interactions between non-bonded atoms and harmonic potentials for bond stretching and bond angle vibrations. Results of the MD simulations determine the critical buckling loads of the BNNTs of various diameters under uniaxial compression, and indicate that for the simulated BNNTs of length L = 6 nm, the critical buckling loads increase by increasing the nanotube diameters.

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