Simulation of Vacancy Pairs in GaN Using Tight-Binding Molecular Dynamics

1997 ◽  
Vol 482 ◽  
Author(s):  
Derrick E. Boucher ◽  
Zoltán A. Gál ◽  
Gary G. DeLeo ◽  
W. Beall Fowler
Keyword(s):  
Molecular Dynamics ◽  
Electronic Structure ◽  
Total Energy ◽  
Formation Energy ◽  
Tight Binding ◽  
Md Simulations ◽  
Shallow Donor ◽  
Shallow Acceptor ◽  
Structure Geometry ◽  
Donor Character

AbstractThe electronic structure, geometry and energetics of Ga vacancy pairs and N vacancy pairs in both wurtzite and zincblende GaN are investigated via molecular dynamics (MD) simulations using an empirical tight-binding (TB) model with total energy capabilities and supercells containing up to 216 atoms. Our calculations suggest that, by pairing, N vacancies, which in isolation act as shallow donors, can lower their collective formation energy by about 5 eV. In doing so, however, these N vacancies lose their shallow-donor character as the lattice relaxes in response to this aggregation. Contrasting with the N vacancies, the Ga vacancies are found to retain their isolated shallow acceptor behavior and do not gain significant energy upon aggregation. The possible implications for larger aggregate defects are discussed.

Molecular Dynamics Study Of Si/Si3N4 Interface

1996 ◽  
Vol 446 ◽  
Author(s):  
Martina E. Bachlechner ◽  
Ingvar Ebbsjö ◽  
Rajiv K. Kalia ◽  
Priya Vashishta
Keyword(s):  
Molecular Dynamics ◽  
Electronic Structure ◽  
Charge Transfer ◽  
Md Simulations ◽  
Electronic Structure Calculations ◽  
Interface Structure ◽  
Bond Bending ◽  
Three Body ◽  
Structure Calculations ◽  
Weber Potential

AbstractStructural correlations at the Si(111)/Si3N4(0001) interface are studied using the molecular dynamics (MD) method. In the bulk, Si is described by the Stillinger-Weber potential and Si3N4 by an interaction potential which contains two-body (steric, Coulomb, electronic polarizabilities) and three-body (bond bending and stretching) terms. At the interface, the charge transfer from silicon to nitrogen is taken from LCAO electronic structure calculations. Using these Si, Si3N4 and interface interactions in MD simulations, the interface structure (atomic positions, bond lengths, and bond angles) is determined. Results for fracture in silicon are also presented.

Tight-binding-molecular-dynamics investigation of the atomic and electronic structure properties of a-C, a-Si and a-SiC

2003 ◽  
Vol 12 (3-7) ◽  
pp. 993-997 ◽  
Author(s):  
V.I. Ivashchenko ◽  
Patrice E.A. Turchi ◽  
V.I. Shevchenko ◽  
L.A. Ivashchenko ◽  
G.V. Rusakov
Keyword(s):  
Molecular Dynamics ◽  
Electronic Structure ◽  
Tight Binding ◽  
Atomic And Electronic Structure ◽  
Structure Properties

New Surface Atomic Structures for III-V(110)-p(1x1)-Sb(1ML):Chemical Bonding and Electronic Structure

1990 ◽  
Vol 193 ◽  
Author(s):  
John P. LaFemina ◽  
C. B. Duke ◽  
C. Maflhiot
Keyword(s):  
Electronic Structure ◽  
Coordination Chemistry ◽  
Total Energy ◽  
Small Molecule ◽  
Chemical Bonding ◽  
Energy Surface ◽  
Minimum Energy ◽  
Tight Binding ◽  
Atomic Structures

ABSTRACTTight-binding total energy computations are used to examine the chemical bonding and electronic structure for two new minimum-energy surface atomic structures for p(lxl) overlayers of Sb on III-V(110) surfaces. The bonding in each of these structures is unique, having no analog in either the bulk or small molecule coordination chemistry of these materials, and is a phenomenon uniquely associated with the constrained epitaxical growth of the Sb overlayer.

A Novel Scheme for Accurate Md Simulations of Large Systems

1997 ◽  
Vol 491 ◽  
Author(s):  
Alessandro De Vita ◽  
Roberto Car
Keyword(s):  
Electronic Structure ◽  
Material Science ◽  
Tight Binding ◽  
Md Simulations ◽  
Model Potential ◽  
Black Box ◽  
Linear Scaling ◽  
Large Systems ◽  
Large Material ◽  
Ab Initio Models

ABSTRACTWe present a simple and informationally efficient approach to electronic-structure-based simulations of large material science systems. The algorithm is based on a flexible embedding scheme, in which the parameters of a model potential are fitted at run time to some precise information relevant to localised portions of the system. Such information is computed separately on small subsystems by electronic-structure “black box” subprograms, e.g. based on tight-binding and/or ab initio models. The scheme allows to enforce electronic structure precision only when and where needed, and to minimise the computed information within a desired accuracy, which can be systematically controlled. Moreover, it is inherently linear scaling, and highly suitable for modern parallel platforms, including those based on non-uniform processing. The method is demonstrated by performing computations of tight-binding accuracy on solid state systems in the ten thousand atoms size scale.

Structure, Bonding and Stability of Transition Metal Silicides: A Real-Space Perspective by Tight Binding Potentials

1997 ◽  
Vol 491 ◽  
Author(s):  
Leo Miglio ◽  
Francesca Tavazza ◽  
Antonio Garbelli ◽  
Massimo Celino
Keyword(s):  
Molecular Dynamics ◽  
Transition Metal ◽  
Total Energy ◽  
Molecular Dynamics Simulations ◽  
Predictive Power ◽  
Tight Binding ◽  
Real Space ◽  
Energy Calculations ◽  
Metal Silicides ◽  
Dynamics Simulations

ABSTRACTWe point out that the predictive power of tight binding potentials is not limited to obtaining fairly accurate total energy calculations and very satisfactory structural evolutions by molecular dynamics simulations. They also allow for a nice physical picture of the links between bonding and stability in different structures, which is particularly helpful in the case of binary suicides

Electronic Structure and Energetics of LaNi5, α-La2Ni10H and β-La2Ni10H14

1998 ◽  
Vol 513 ◽  
Author(s):  
H. Nakamura ◽  
D. Nguyen-Manh ◽  
D. G. Pettifor
Keyword(s):  
Electronic Structure ◽  
Total Energy ◽  
Charge Density ◽  
Tight Binding ◽  
Site Occupancy ◽  
Heat Of Formation ◽  
Hydrogen Atoms ◽  
Atomic Sphere ◽  
Sphere Approximation ◽  
Atomic Sphere Approximation

ABSTRACTThe electronic structure and energetics of LaNi5, its hydrogen solution (α-La2Ni10H) and its hydride (β-La2Ni10H14) were investigated by means of the tight-binding linear muffin-tin orbitals method within the atomic sphere approximation (TB-LMTO-ASA). Preferred site occupancy by the absorbed hydrogen atoms was investigated in terms of the charge density of the interstitial sites and the total energy, both of which indicate that the 6m site in the P6/mmm symmetry is the most preferred. A negative heat of formation of La2Ni10H14 was obtained from the total energy calculations.

Tight-binding description of the electronic structure and total energy of tin

2002 ◽  
Vol 82 (1) ◽  
pp. 47-61 ◽  
Author(s):  
Brahim Akdim ◽  
D. A. Papaconstantopoulos ◽  
M. J. Mehl
Keyword(s):  
Electronic Structure ◽  
Total Energy ◽  
Tight Binding

NON-COLLINEAR MAGNETISM IN THE Fe3 MICROCLUSTER: FREE-STANDING VS SUPPORTED ENVIRONMENTS

2005 ◽  
Vol 19 (15n17) ◽  
pp. 2532-2537
Author(s):  
E. MARTÍNEZ ◽  
R. ROBLES ◽  
A. VEGA ◽  
R. C. LONGO ◽  
L. J. GALLEGO
Keyword(s):  
Molecular Dynamics ◽  
Magnetic Properties ◽  
Electronic Structure ◽  
Tight Binding ◽  
Geometrical Configuration ◽  
Free Standing ◽  
Embedded Atom ◽  
Self Consistent ◽  
Tight Binding Method ◽  
Dynamics Simulations

The possibility of a non-collinear magnetic configuration of the Fe 3 microcluster supported on the Ni (001) surface has been investigated. The morphology of the supported cluster has been calculated by means of the modified embedded atom model with quenched molecular dynamics simulations, and the electronic structure for the most stable geometrical configuration has been studied using a self-consistent non-collinear spd tight-binding method parameterised to ab-initio tight-binding linear muffin tin orbital results. Our predictions are compared with previous results for the free-standing Fe 3 microcluster. The influence of the substrate in both the structure and the magnetic properties, particularly the onset of non-collinear magnetism, is discussed in detail.

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