Atomistic Study of Boron-Doped Silicon

1995 ◽  
Vol 408 ◽  
Author(s):  
M. Fearn ◽  
J. H. Jefferson ◽  
D. G. Pettifor
Keyword(s):  
Charge State ◽  
Density Functional ◽  
Chemical Potential ◽  
Tetrahedral Site ◽  
Tight Binding ◽  
Near Neighbor ◽  
Boron Diffusion ◽  
Binding Model ◽  
Teller Distortion ◽  
Silicon Vacancy

AbstractAtomistic simulations using both tight-binding and density-functional approaches have been performed to investigate boron-related defects in silicon. In agreement with experiment, the boron interstitial is shown to be a negative- U center in the sense that its neutral charge state, with an associated Jahn-Teller distortion off the ideal tetrahedral site, is never the ground state for any value of the chemical potential in the gap. The possible consequences for an electron-assisted migration of the interstitial are discussed. We also find the boron substitutional defect to be a next-nearest neighbor of a silicon vacancy in agreement with EPR spectra.A semi-empirical tight-binding model of the boron-silicon system is validated by direct comparison with the accurate density-functional results and is then used to perform molecular dynamics simulations of boron diffusion at high temperatures. The mobility of the interstitial is found to be strongly charge-state dependent. Termination of the boron interstitial migration path by recombination with a silicon vacancy is shown to be a very likely process with a number of configurations having no barrier to capture when the boron is a near-neighbor of the vacancy.

scholarly journals Single-crystalline epitaxial TiO film: A metal and superconductor, similar to Ti metal

2021 ◽  
Vol 7 (2) ◽  
pp. eabd4248
Author(s):  
Fengmiao Li ◽  
Yuting Zou ◽  
Myung-Geun Han ◽  
Kateryna Foyevtsova ◽  
Hyungki Shin ◽  
...  
Keyword(s):  
Transition Metal ◽  
Density Functional ◽  
Tight Binding ◽  
Crystal Form ◽  
Titanium Monoxide ◽  
Binding Model ◽  
Functional Theory ◽  
Single Crystalline ◽  
First Time ◽  
Lattice Matched

Titanium monoxide (TiO), an important member of the rock salt 3d transition-metal monoxides, has not been studied in the stoichiometric single-crystal form. It has been challenging to prepare stoichiometric TiO due to the highly reactive Ti2+. We adapt a closely lattice-matched MgO(001) substrate and report the successful growth of single-crystalline TiO(001) film using molecular beam epitaxy. This enables a first-time study of stoichiometric TiO thin films, showing that TiO is metal but in proximity to Mott insulating state. We observe a transition to the superconducting phase below 0.5 K close to that of Ti metal. Density functional theory (DFT) and a DFT-based tight-binding model demonstrate the extreme importance of direct Ti–Ti bonding in TiO, suggesting that similar superconductivity exists in TiO and Ti metal. Our work introduces the new concept that TiO behaves more similar to its metal counterpart, distinguishing it from other 3d transition-metal monoxides.

Investigating 3,4-bis(3-nitrofurazan-4-yl)furoxan detonation with a rapidly tuned density functional tight binding model

2021 ◽  
Vol 154 (16) ◽  
pp. 164115
Author(s):  
Rebecca K. Lindsey ◽  
Sorin Bastea ◽  
Nir Goldman ◽  
Laurence E. Fried
Keyword(s):  
Density Functional ◽  
Tight Binding ◽  
Tight Binding Model ◽  
Binding Model

scholarly journals A Density Functional Tight Binding Model with an Extended Basis Set and Three-Body Repulsion for Hydrogen under Extreme Thermodynamic Conditions

2014 ◽  
Vol 118 (29) ◽  
pp. 5520-5528 ◽  
Author(s):  
Sriram Goverapet Srinivasan ◽  
Nir Goldman ◽  
Isaac Tamblyn ◽  
Sebastien Hamel ◽  
Michael Gaus
Keyword(s):  
Density Functional ◽  
Tight Binding ◽  
Basis Set ◽  
Tight Binding Model ◽  
Binding Model ◽  
Thermodynamic Conditions ◽  
Three Body ◽  
Extended Basis

Electronic Structure of Fullerene Tubules

1992 ◽  
Vol 247 ◽  
Author(s):  
J. W. Mintmire ◽  
D. H. Robertson ◽  
B. I. Dunlap ◽  
R. C. Mowrey ◽  
D. W. Brenner ◽  
...  
Keyword(s):  
First Principles ◽  
Density Functional ◽  
Local Density ◽  
Tight Binding ◽  
Small Diameter ◽  
High Symmetry ◽  
Binding Model ◽  
High Carrier ◽  
Reasonable Description ◽  
Gaussian Orbital

ABSTRACTRecent reports suggest that graphitic tubules with diameters on the order of fullerene diameters have been synthesized. Such small-diameter tubules should have electronic properties related to those of two-dimensional graphite. We demonstrate by comparison with results from a first-principles, self-consistent, all-electron Gaussian-orbital based local-density functional approach that an all-valence tight-binding model can be expected to give a reasonable description of the electronic states of these tubules. In analyzing both high-symmetry tubules and lower-symmetry chiral tubules, we see that a relatively high carrier density could be expected for many of these structures.

scholarly journals Disorder-induced suppression of the zero-bias conductance peak splitting in topological superconducting nanowires

2018 ◽  
Vol 9 ◽  
pp. 1358-1369 ◽  
Author(s):  
Jun-Tong Ren ◽  
Hai-Feng Lü ◽  
Sha-Sha Ke ◽  
Yong Guo ◽  
Huai-Wu Zhang
Keyword(s):  
Bound States ◽  
Chemical Potential ◽  
Zero Mode ◽  
Tight Binding ◽  
Fano Factor ◽  
Energy Splitting ◽  
Binding Model ◽  
Superconducting Nanowires ◽  
Zero Bias ◽  
Conductance Peak

We investigate the effect of three types of intrinsic disorder, including that in pairing energy, chemical potential, and hopping amplitude, on the transport properties through the superconducting nanowires with Majorana bound states (MBSs). The conductance and the noise Fano factor are calculated based on a tight-binding model by adopting a non-equilibrium Green’s function method. It is found that the disorder can effectively lead to a reduction in the conductance peak spacings and significantly suppress the peak height. Remarkably, for a longer nanowire, the zero-bias peak could be reproduced by weak disorder for a finite Majorana energy splitting. It is interesting that the shot noise provides a signature to discriminate whether the zero-bias peak is induced by Majorana zero mode or disorder. For Majorana zero mode, the noise Fano factor approaches zero in the low bias voltage limit due to the resonant Andreev tunneling. However, the Fano factor is finite in the case of a disorder-induced zero-bias peak.

Quantum molecular dynamics simulation of Σ13 grain boundary in Si

1992 ◽  
Vol 50 (1) ◽  
pp. 212-213
Author(s):  
M.J. Kim ◽  
H. Ma ◽  
R.W. Carpenter ◽  
S.H. Lin ◽  
O.F. Sankey
Keyword(s):  
Molecular Dynamics ◽  
Grain Boundary ◽  
Density Functional ◽  
Local Density ◽  
Tight Binding ◽  
Equilibrium Structure ◽  
Dynamics Simulation ◽  
Boundary Structure ◽  
Quantum Molecular Dynamics ◽  
Binding Model

Grain boundary (GB) structure determination at an atomic level by HREM had received increasing attention in recent years. However, models of grain boundary structure deduced from the experiment results are usually not unique, and they do not necessarily represent the equilibrium structure. A newly developed quantum-molecular-dynamics (QMD) method, which does not depend on any empirical potentials, can be used to test these models and find the equilibrium atomic structure through simulated quenching. The method employs an electronic structure tight-binding model based on density functional theory within the local density approximation and the nonlocal pseudopotential scheme, and is used to compute the total energy and atomic forces for a variety of covalent materials. In the present study, this QMD method, coupled with image simulation, was used to predict the relaxed atomic configuration for the Σ=13 (510), [001] tilt grain boundary in Si.

scholarly journals Determination of a Density Functional Tight Binding Model with an Extended Basis Set and Three-Body Repulsion for Carbon Under Extreme Pressures and Temperatures

2013 ◽  
Vol 117 (15) ◽  
pp. 7885-7894 ◽  
Author(s):  
Nir Goldman ◽  
Sriram Goverapet Srinivasan ◽  
Sebastien Hamel ◽  
Laurence E. Fried ◽  
Michael Gaus ◽  
...  
Keyword(s):  
Density Functional ◽  
Tight Binding ◽  
Basis Set ◽  
Tight Binding Model ◽  
Binding Model ◽  
Three Body ◽  
Extended Basis

Composition and Strain Dependence of the Piezoelectric Coefficients in Semiconductor Alloys

2007 ◽  
Vol 1017 ◽  
Author(s):  
T. Hammerschmidt ◽  
M. A. Migliorato ◽  
D. Powell ◽  
A. G. Cullis ◽  
G. P. Srivastava
Keyword(s):  
First Principles ◽  
Density Functional ◽  
Piezoelectric Coefficient ◽  
Tight Binding ◽  
Tight Binding Model ◽  
Semiconductor Alloys ◽  
Binding Model ◽  
Functional Theory ◽  
Photo Current ◽  
Good Agreement

AbstractWe propose a tight-binding model for the polarization that considers direct and dipole contributions and employs microscopic quantities that can be calculated by first-principles methods, e.g. by employing Density Functional Theory (DFT). Applying our model to InxGa1-xAs alloys allows us to settle discrepancies between the values of e14 as obtained from experiments and from linear interpolations between the values of InAs and GaAs. Our calculated piezoelectric coefficient is in very good agreement with photo current measurements of InAs/GaAs(111) quantum well samples.

scholarly journals Quantum spin-valley Hall effect in AB-stacked bilayer silicene

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Kyu Won Lee ◽  
Cheol Eui Lee
Keyword(s):  
Hall Effect ◽  
Density Functional ◽  
Tight Binding ◽  
Quantum Spin ◽  
Chern Number ◽  
Antiferromagnetic Order ◽  
Gradual Change ◽  
Edge States ◽  
Binding Model ◽  
Valley Hall Effect

AbstractOur density functional theory calculations show that while AB-stacked bilayer silicene has a non-quantized spin-valley Chern number, there exist backscattering-free gapless edge states within the bulk gap, leading to a quantum spin-valley Hall effect. Using a tight-binding model for a honeycomb bilayer, we found that the interlayer potential difference and the staggered AB-sublattice potential lead to abrupt and gradual change of the valley Chern number from a quantized value to zero, respectively, while maintaining backscattering-free gapless edge states if the valley Chern number is not too close to zero. Under an inversion symmetry-breaking potential in the form of the staggered AB-sublattice potential, such as an antiferromagnetic order and a hexagonal diatomic sheet, a finite but non-quantized (spin-)valley Chern number can correspond to a quantum (spin-)valley Hall insulator.

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