New Tight-Binding Pair Potentials for Mineral Oxides: Application to β-Cassiterite (110), β-Tridymite (10TO) and Cristobalite (110)

1992 ◽  
Vol 278 ◽  
Author(s):  
T. J. Godin ◽  
John P. Lafemina
Keyword(s):  
Total Energy ◽  
Nearest Neighbor ◽  
Tight Binding ◽  
Insulating Materials ◽  
Atomic Structures ◽  
Pair Potentials ◽  
Mineral Oxides ◽  
Distant Neighbor

AbstractTight-binding, total-energy (TBTE) methods have successfully predicted surface atomic geometries for a variety of semiconducting and insulating materials that are well described by a nearest-neighbor model of interatomic interactions. However, little work has been done on distant-neighbor models, which are required to study many important mineral oxides. In this paper we demonstrate one way in which the TBTE methodology can be extended to these materials. To illustrate this approach, we calculate surface atomic structures for cassiterite SnO2 (110), β-cristobalite SiO2 (110) and βtridymite SiO2 (10TO).

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.

scholarly journals Density-functional Based Tight-binding Calculations on Thiophene Polymorphism

VLSI Design ◽  
2001 ◽  
Vol 13 (1-4) ◽  
pp. 393-397
Author(s):  
J. Widany ◽  
G. Daminelli ◽  
A. Di Carlo ◽  
P. Lugli
Keyword(s):  
Total Energy ◽  
Intermolecular Interaction ◽  
Density Functional ◽  
Tight Binding ◽  
Methyl Groups ◽  
Direct Function ◽  
Energy Calculations ◽  
Polymorphic Modifications

Total energy calculations based on a density-functional tight-binding scheme have been performed on polymorphic modifications of various thiophene crystals. The investigated structures include sulphanyl-substituted quater-thiophene and methyl-substituted sexithiophene, in the monoclinic and triclinic modifications. Attention has been focused on the intermolecular interaction between the molecular units. Despite the similarities in the backbone geometries, the strength and nature of intermolecular interaction differs largely in the various polymorphs. Sulphur atoms belonging to the thiophene rings are strongly involved in the interaction. Sulphanyl substituents play an important role, while methyl groups do not contribute. The strength of intermolecular interaction is not a direct function of atom distance.

Electrical Transport Properties of Carbon Nanotube Metal-Semiconductor Heterojunction

2016 ◽  
Vol 15 (05n06) ◽  
pp. 1660009 ◽  
Author(s):  
Keka Talukdar ◽  
Anil Shantappa
Keyword(s):  
Electrical Transport ◽  
Nearest Neighbor ◽  
Electronic Devices ◽  
Tight Binding ◽  
Transmission Function ◽  
Topological Defects ◽  
Dynamics Simulation ◽  
Internal Stresses ◽  
Electrical Transport Properties ◽  
Tight Binding Approximation

Carbon nanotubes (CNTs) have been proved to have promising applicability in various fields of science and technology. Their fascinating mechanical, electrical, thermal, optical properties have caught the attention of today’s world. We have discussed here the great possibility of using CNTs in electronic devices. CNTs can be both metallic and semiconducting depending on their chirality. When two CNTs of different chirality are joined together via topological defects, they may acquire rectifying diode property. We have joined two tubes of different chiralities through circumferential Stone–Wales defects and calculated their density of states by nearest neighbor tight binding approximation. Transmission function is also calculated to analyze whether the junctions can be used as electronic devices. Different heterojunctions are modeled and analyzed in this study. Internal stresses in the heterojunctions are also calculated by molecular dynamics simulation.

scholarly journals Accurate six-band nearest-neighbor tight-binding model for the π-bands of bulk graphene and graphene nanoribbons

2011 ◽  
Vol 109 (10) ◽  
pp. 104304 ◽  
Author(s):  
Timothy B. Boykin ◽  
Mathieu Luisier ◽  
Gerhard Klimeck ◽  
Xueping Jiang ◽  
Neerav Kharche ◽  
...  
Keyword(s):  
Nearest Neighbor ◽  
Graphene Nanoribbons ◽  
Tight Binding ◽  
Tight Binding Model ◽  
Binding Model

scholarly journals ON THE VERDET CONSTANT AND FARADAY ROTATION FOR GRAPHENE-LIKE MATERIALS

2013 ◽  
Vol 25 (04) ◽  
pp. 1350007 ◽  
Author(s):  
MIKKEL H. BRYNILDSEN ◽  
HORIA D. CORNEAN
Keyword(s):  
Taylor Expansion ◽  
Nearest Neighbor ◽  
Tight Binding ◽  
Transverse Component ◽  
Tight Binding Model ◽  
Binding Model ◽  
Gauge Invariant ◽  
Verdet Constant ◽  
Absolute Value ◽  
Computable Formula

We present a rigorous and rather self-contained analysis of the Verdet constant in graphene-like materials. We apply the gauge-invariant magnetic perturbation theory to a nearest-neighbor tight-binding model and obtain a relatively simple and exactly computable formula for the Verdet constant, at all temperatures and all frequencies of sufficiently large absolute value. Moreover, for the standard nearest-neighbor tight-binding model of graphene we show that the transverse component of the conductivity tensor has an asymptotic Taylor expansion in the external magnetic field where all the coefficients of even powers are zero.

Transfer Integrals and Band Structures in (Et)2X Salts

1989 ◽  
Vol 173 ◽  
Author(s):  
Oliver H. Leblanc ◽  
Margaret L. Blohm ◽  
Richard P. Messmer
Keyword(s):  
Low Temperature ◽  
Nearest Neighbor ◽  
Spherical Wave ◽  
Tight Binding ◽  
Ab Initio Method ◽  
Energy Bands ◽  
Hubbard Hamiltonian ◽  
Transfer Integrals ◽  
Semi Empirical ◽  
Very Low Temperature

ABSTRACTTransfer integrals (tij) between pairs of nearest neighbor ET molecules were calculated by an ab initio method. Tight-binding one-electron energy bands constructed from the tij are similar to those previously calculated by Mori and by Whangbo and their coworkers by semi-empirical, extended Hückel methods, but quite different from those found by Kübler et al. in β-(ET)2I3 using the augmented spherical wave (ASW) method. However, all these band models are suspect. The Hubbard on-site repulsion parameter U is estimated to be about twice the band widths, indicating that a full treatment of the Hubbard hamiltonian is needed. Also, polaron effects appear to control transport except at very low temperature.

Local Atomic Structures in Amorphous and Quasicrystalline Zr70Ni10Pt20and Zr80Pt20Alloys by the Anomalous X-ray Scattering Method

2000 ◽  
Vol 644 ◽  
Author(s):  
Eiichiro Matsubara ◽  
Takahiro Nakamura ◽  
Masaki Sakurai ◽  
Muneyuki Imafuku ◽  
Shigeo Sato ◽  
...  
Keyword(s):  
Short Range ◽  
Short Range Order ◽  
Nearest Neighbor ◽  
Scattering Method ◽  
X Ray ◽  
Coordination Numbers ◽  
Atomic Structures ◽  
X Ray Scattering ◽  
Icosahedral Clusters ◽  
Ray Scattering

AbstractLocal atomic structures around Zr and Pt in a quasicrystalline Zr80Pt20alloy, and amorphous and quasicrystalline Zr70Ni10Pt20alloys have been determined by the anomalous x-ray scattering (AXS) method. A distinct prepeak observed in an intensity profile of the amorphous Zr70Ni10Pt20alloy indicates existence of strong chemical short-range order (CSRO) clusters in the amorphous phase. Total coordination numbers around Zr and Pt in a nearest neighbor region in both alloys have been evaluated. The values around Pt are almost equal to 12 in the amorphous and quasicrystalline states suggest formation of icosahedral clusters around Pt. Some of crystalline structures formed from the quasicrystalline phases by annealing consist of icosahedral clusters of Zr and Ni atoms, or polyhedral clusters of Zr and Pt atoms similar with icosahedral clusters. The present result appears to support that the phase transformation from the amorphous to the crystal through the quasicrystal is explained by the icosahedral CSRO clusters in the amorphous and quasicrystalline states.

scholarly journals New Ternary Compounds of the Composition Cu2SnTi3 and Their Crystal Structures

2020 ◽  
Vol 10 (24) ◽  
pp. 8776
Author(s):  
Sheng-Fang Huang ◽  
Yen-Cheng Chang ◽  
Po-Liang Liu
Keyword(s):  
Crystal Structure ◽  
Total Energy ◽  
Ternary Compound ◽  
Density Functional ◽  
Hexagonal Crystal Structure ◽  
X Ray Diffraction ◽  
Hexagonal Crystal ◽  
Orthorhombic Crystal Structure ◽  
X Ray ◽  
Atomic Structures

A new ternary compound Cu2SnTi3 has been synthesized by vacuum sintering at 900 °C. The atomic structures of CaCu5- and InNi2-like Cu2SnTi3 are calculated using density functional theory methods. The X-ray diffraction (XRD) analysis and selected area diffraction (SAD) patterns of the new ternary compound Cu2SnTi3 are considered to verify the atomic structures of CaCu5- and InNi2-like Cu2SnTi3. The results reveal that the InNi2-like Cu2SnTi3 model has the lowest total energy of −35.239 eV, representing the trigonal crystal structure. The orthorhombic crystal structure of the CaCu5-like Cu2SnTi3 model has the second lowest total energy of −33.926 eV. Our theoretical X-ray diffraction peak profiles of InNi2-like (CaCu5-like) Cu2SnTi3 are nearly identical to experimental one, leading to an error below 2.0% (3.0%). In addition, the hexagonal crystal structure of the CaCu5-like Cu2SnTi3 model has the highest total energy of −33.094 eV. The stability of the Cu2SnTi3 in terms of energy follows the order: the trigonal, orthorhombic, and hexagonal crystal structure.

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.

Sign in / Sign up

Export Citation Format

Share Document