Structural Disorder and Localized Gap States in Silicon Grain Boundaries from a Tight-Binding Model

1997 ◽  
Vol 491 ◽  
Author(s):  
F. Cleri ◽  
P. Keblinski ◽  
L. Colombo ◽  
S. R. Phillpot ◽  
D. Wolf
Keyword(s):  
Molecular Dynamics ◽  
Grain Boundaries ◽  
Tight Binding ◽  
Structural Disorder ◽  
High Energy ◽  
Tight Binding Model ◽  
Binding Model ◽  
Dynamics Simulations ◽  
Gap States ◽  
Forbidden Gap

ABSTRACTTight-binding molecular dynamics simulations of typical high-energy grain boundaries in silicon show that the atomic structure of the interface in thermodynamic equilibrium is similar to that of bulk amorphous silicon and contains coordination defects. The corresponding electronic structure is also amorphous-like, displaying extra states in the forbidden gap mainly localized around the coordination defects, where large changes in the bond-hybridization character are observed. It is proposed that such coordination defects in disordered high-energy grain boundaries are responsible for the experimentally observed gap states in polycrystalline Si.

scholarly journals Incomplete melting of the Si(100) surface from molecular-dynamics simulations using the effective-medium tight-binding model

1996 ◽  
Vol 360 (1-3) ◽  
pp. 221-228 ◽  
Author(s):  
K. Stokbro ◽  
K.W. Jacobsen ◽  
J.K. Nørskov ◽  
D.M. Deaven ◽  
C.Z. Wang ◽  
...  
Keyword(s):  
Molecular Dynamics ◽  
Molecular Dynamics Simulations ◽  
Tight Binding ◽  
Effective Medium ◽  
Tight Binding Model ◽  
Binding Model ◽  
Dynamics Simulations

scholarly journals Molecular Dynamics Simulation of Impurities in Nanocrystalline Diamond Grain Boundaries

1999 ◽  
Vol 593 ◽  
Author(s):  
Michael Sternberg ◽  
Peter Zapoll ◽  
Thomas Frauenheim ◽  
Dieter M. Gruen ◽  
Larry A. Curtiss
Keyword(s):  
Molecular Dynamics ◽  
Grain Boundaries ◽  
Density Functional ◽  
Tight Binding ◽  
High Energy ◽  
Nanocrystalline Diamond ◽  
Dynamics Simulation ◽  
Si Substrates ◽  
Dynamics Simulations ◽  
Diamond Grain

ABSTRACTNanocrystalline diamond films grown on Si substrates at 800°C from hydrogen-poorplasmas have a number of highly desirable mechanical and electronic properties. Impurities were found by SIMS measurements to be uniformly distributed throughout the thickness of the films at a level of 1017–1018 cm−3. It is likely that the impurities are located at the grain boundaries, which play a crucial role in controlling important characteristics of the films, such as electrical conductivity and electron emission. Density-functional based tight-binding (DFTB) molecular dynamics simulations were performed for diamond high-energy high-angle (100) twist grain boundaries with impurities such as N, Si and H

An Ab-Initio Multicenter Tight-Binding Model for Molecular Dynamics Simulations

1988 ◽  
Vol 141 ◽  
Author(s):  
Otto F. Sankey ◽  
David J. Niklewski
Keyword(s):  
Molecular Dynamics ◽  
Molecular Dynamics Simulations ◽  
Local Density ◽  
Tight Binding ◽  
Real Space ◽  
Hamiltonian Matrix ◽  
Binding Model ◽  
Annealing Study ◽  
Total Energies ◽  
Dynamics Simulations

AbstractA new, approximate method has been developed for computing total energies and forces for a variety of applications including molecular dynamics simulations of covalent materials. The method is tight-binding-like and is based on the local density approximation within the pseudopotential scheme. Slightly excited pseudo-atomic-orbitals are used, and the tight-binding Hamiltonian matrix is obtained in real space. The method is used to find the total energies for five crystalline phases of Si and the Si 2 molecule. Excellent agreement is found with experiment. A molecular dynamics simulated annealing study has been performed on the Si 3 molecule to determine the ground state configuration.

ISOMERS OF COPPER CLUSTERS OBTAINED BY A MOLECULAR DYNAMICS MODEL

2005 ◽  
Vol 19 (15n17) ◽  
pp. 2359-2364
Author(s):  
LING WANG ◽  
XI-JING NING
Keyword(s):  
Molecular Dynamics ◽  
Tight Binding ◽  
Magic Number ◽  
Tight Binding Model ◽  
Dynamics Model ◽  
Binding Model ◽  
Higher Symmetry ◽  
Empirical Potential ◽  
Copper Clusters ◽  
Moment Approximation

A molecular dynamics model was developed to search for stable copper clusters with up to 60 atoms by Gupts empirical potential based on the second-moment approximation to tight-binding model (TB-SMA). We found that isomers do not emerge until the clusters have more than 7 atoms, getting more for clusters with 30~52 atoms, and the magic number, 13, 19, 23, 26, 28, 32, 38, 43, 46, 49, and 55 have ground clusters with higher symmetry and have few isomers.

A Tight-Binding Model for Molecular Dynamics of Carbon-Hydrogen Systems

1994 ◽  
Vol 358 ◽  
Author(s):  
G. Kopidakis ◽  
C.Z. Wang ◽  
C.M. Soukoulis ◽  
K.M. Ho
Keyword(s):  
Molecular Dynamics ◽  
Ab Initio ◽  
Tight Binding ◽  
Carbon Clusters ◽  
Vibrational Properties ◽  
Tight Binding Model ◽  
Binding Model ◽  
Hydrocarbon Molecules ◽  
Hydrogen Systems

ABSTRACTA model for studying carbon-hydrogen systems with molecular dynamics (MD) is developed based on an empirical tight-binding approach for the calculation of the interatomic forces. The parameters involved are obtained by fitting to the structure of methane. The transferability of the model is tested by reproducing accurately several electronic, structural, and vibrational properties of hydrocarbon molecules. Ab initio results on carbon clusters with hydrogen are compared with the results obtained with our model.

Magnetic Spin Susceptibility of Graphene in Ferromagnetic State: A Tight-Binding Model Study

SPIN ◽  
2020 ◽  
Vol 10 (01) ◽  
pp. 2050004
Author(s):  
Sivabrata Sahu ◽  
G. C. Rout
Keyword(s):  
Coulomb Interaction ◽  
Tight Binding ◽  
High Energy ◽  
Spin Susceptibility ◽  
Function Technique ◽  
Tight Binding Model ◽  
Transfer Energy ◽  
Binding Model ◽  
Frequency Dependent ◽  
Model Study

We report here a tight-binding model study of frequency-dependent ferromagnetic spin susceptibility of the graphene system. The tight-binding Hamiltonian consists of electron hoppings up to third-nearest-neighbors, substrate and impurity effects in the presence of Coulomb interaction of electrons separately at two in-equivalent A and B sub-lattices of graphene. To calculate magnetic susceptibility, we calculate the two-particle electron Green’s functions by using Zubarev’s double time Green’s function technique. The electron occupations at A and B sub-lattices for both up and down spins are computed numerically and self-consistently. The frequency-dependent real part of ferromagnetic susceptibility of the system is computed numerically by taking [Formula: see text] grid points of the electron momentum. The susceptibility displays a sharp peak at the neutron momentum transfer energy at low energies and another higher energy resonance peak appearing at substrate-induced gap. The [Formula: see text]-peak shifts to a higher energy with the increase of momentum [Formula: see text]. The susceptibility shows that the high energy peak shifts to higher energies due to the corresponding increase of substrate-induced gap observed experimentally. It is observed that the Coulomb interaction suppresses the substrate-induced gap, but the impurity doping at A site enhances the substrate-induced gap, while doping at B site suppresses it.

Deformation and Fracture of Metallic Nanowires

2016 ◽  
Vol 258 ◽  
pp. 277-280 ◽  
Author(s):  
Mohamed Mahmud Aish ◽  
Mikhail D. Starostenkov
Keyword(s):  
Molecular Dynamics ◽  
Interatomic Potential ◽  
Tight Binding ◽  
Three Dimensional ◽  
Dynamics Simulation ◽  
Metallic Nanowires ◽  
Many Body ◽  
Binding Model ◽  
Deformation And Fracture ◽  
Dynamics Simulations

A many-body interatomic potential for metallic nanowires within the second-moment approximation of the tight-binding model (the Cleri-Rosato potential) was employed to carry out three dimensional molecular dynamics simulations. Molecular dynamics simulation results for metallic nanowires at various temperature are presented. The stress–time and stress length curves for nanowires are simulated. The breaking and yield stress of nanowires are dependent on the Volume and temperature. The necking, Plastic deformation, slipping domain, twins, clusters, microspores and break-up phenomena of nanowire are demonstrated. Stress decreases with increasing nanowire volume and temperature. The final breaking position occurs at the central part of the nanowire when it is short, as the nanowire length increases the breaking position gradually shifts to the ends.

scholarly journals Comparison of the Structure of Grain Boundaries in Silicon and Diamond by Molecular-Dynamics Simulations

1997 ◽  
Vol 472 ◽  
Author(s):  
P. Keblinski ◽  
S. R. Phillpot ◽  
D. Wolf ◽  
H. Gleiter
Keyword(s):  
Molecular Dynamics ◽  
Grain Size ◽  
Molecular Dynamics Simulations ◽  
Grain Boundaries ◽  
Amorphous Silicon ◽  
Electrical Conduction ◽  
Large Fraction ◽  
Nanocrystalline Silicon ◽  
High Energy ◽  
Dynamics Simulations

ABSTRACTMolecular-dynamics simulations were used to synthesize nanocrystalline silicon with a grain size of up to 75 Å by crystallization of randomly misoriented crystalline seeds from the melt. The structures of the highly-constrained interfaces in the nanocrystal were found to be essentially indistinguishable from those of high-energy bicrystalline grain boundaries (GBs) and similar to the structure of amorphous silicon. Despite disorder, these GBs exhibit predominantly four-coordinated (sp3-like) atoms and therefore have very few dangling bonds. By contrast, the majority of the atoms in high-energy bicrystalline GBs in diamond are three-coordinated (sp2-like). Despite the large fraction of three-coordinated GB carbon atoms, they are rather poorly connected amongst themselves, thus likely preventing any type of graphite-like electrical conduction through the GBs.

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