Tight Binding Methods for Metallic Systems

2011 ◽  
Keyword(s):  
Tight Binding ◽  
Metallic Systems

scholarly journals Environment-Dependent Tight-Binding Potential Model

1997 ◽  
Vol 491 ◽  
Author(s):  
C. Z. Wang ◽  
B. C. Pan ◽  
M. S. Tang ◽  
H. Haas ◽  
M. Sígalas ◽  
...  
Keyword(s):  
Potential Model ◽  
Tight Binding ◽  
Binding Potential ◽  
Tight Binding Model ◽  
Binding Parameters ◽  
Binding Model ◽  
Structures And Properties ◽  
Metallic Systems

ABSTRACTWe have developed a tight-binding model which goes beyond the traditional two-center approximation and allows the tight-binding parameters to scale according to the bonding environment. Our studies show that this environment-dependent tight-binding model improves remarkably the accuracy and transferability of the potential to describe the structures and properties of higher coordinated metallic systems in addition to those of low coordinated covalent systems.

scholarly journals ELECTRONIC TRANSPORT IN METALLIC SYSTEMS AND GENERALIZED KINETIC EQUATIONS

2011 ◽  
Vol 25 (23n24) ◽  
pp. 3071-3183 ◽  
Author(s):  
A. L. KUZEMSKY
Keyword(s):  
Electrical Conductivity ◽  
Electron Transport ◽  
Transition Metals ◽  
Tight Binding ◽  
Kinetic Equations ◽  
Transport Processes ◽  
Theoretical Formulation ◽  
Tight Binding Approximation ◽  
Model Approach ◽  
Metallic Systems

This paper reviews some selected approaches to the description of transport properties, mainly electroconductivity, in crystalline and disordered metallic systems. A detailed qualitative theoretical formulation of the electron transport processes in metallic systems within a model approach is given. Generalized kinetic equations which were derived by the method of the nonequilibrium statistical operator are used. Tight-binding picture and modified tight-binding approximation (MTBA) were used for describing the electron subsystem and the electron-lattice interaction correspondingly. The low- and high-temperature behavior of the resistivity was discussed in detail. The main objects of discussion are nonmagnetic (or paramagnetic) transition metals and their disordered alloys. The choice of topics and the emphasis on concepts and model approach makes it a good method for a better understanding of the electrical conductivity of the transition metals and their disordered binary substitutional alloys, but the formalism developed can be applied (with suitable modification), in principle, to other systems. The approach we used and the results obtained complements the existent theories of the electrical conductivity in metallic systems. The present study extends the standard theoretical format and calculation procedures in the theories of electron transport in solids.

Molecular-Dynamics Simulations of Magnetic Structures in Metallic Systems

2001 ◽  
Vol 677 ◽  
Author(s):  
Ralf Meyer ◽  
Laurent J. Lewis
Keyword(s):  
Molecular Dynamics ◽  
Molecular Dynamics Simulations ◽  
Rotational Symmetry ◽  
Tight Binding ◽  
Exchange Interactions ◽  
Magnetic Structures ◽  
Simulated System ◽  
Dynamics Simulations ◽  
Metallic Systems ◽  
Improved Algorithm

ABSTRACTRecently a method has been proposed which allows the calculation of complex magnetic structures from a simple d-band tight-binding Hamiltonian including Coulomb and exchange interactions with the help of a molecular-dynamics simulations. In this article an improved version of this ap- proach is suggested which retains the rotational symmetry of the simulated system. The improved algorithm is applied to systems with electron numbers in the range 7 ≤nd ≤ 8.

Vapour Pressure Isotope Effect on Evaporation from Pure Organic Phases - a PIMD Approach

2020 ◽  
Author(s):  
Luis Vasquez ◽  
Agnieszka Dybala-Defratyka
Keyword(s):  
Path Integral ◽  
Vapour Pressure ◽  
Density Functional ◽  
Isotope Effects ◽  
Tight Binding ◽  
Decomposition Analysis ◽  
Energy Decomposition Analysis ◽  
Special Importance ◽  
Non Covalent Interactions ◽  
Covalent Interactions

<p></p><p>Very often in order to understand physical and chemical processes taking place among several phases fractionation of naturally abundant isotopes is monitored. Its measurement can be accompanied by theoretical determination to provide a more insightful interpretation of observed phenomena. Predictions are challenging due to the complexity of the effects involved in fractionation such as solvent effects and non-covalent interactions governing the behavior of the system which results in the necessity of using large models of those systems. This is sometimes a bottleneck and limits the theoretical description to only a few methods.<br> In this work vapour pressure isotope effects on evaporation from various organic solvents (ethanol, bromobenzene, dibromomethane, and trichloromethane) in the pure phase are estimated by combining force field or self-consistent charge density-functional tight-binding (SCC-DFTB) atomistic simulations with path integral principle. Furthermore, the recently developed Suzuki-Chin path integral is tested. In general, isotope effects are predicted qualitatively for most of the cases, however, the distinction between position-specific isotope effects observed for ethanol was only reproduced by SCC-DFTB, which indicates the importance of using non-harmonic bond approximations.<br> Energy decomposition analysis performed using the symmetry-adapted perturbation theory (SAPT) revealed sometimes quite substantial differences in interaction energy depending on whether the studied system was treated classically or quantum mechanically. Those observed differences might be the source of different magnitudes of isotope effects predicted using these two different levels of theory which is of special importance for the systems governed by non-covalent interactions.</p><br><p></p>

Quasi-Barrierless Submolecular Motion in Mechanically Interlocked Carbon Nanotubes

2020 ◽  
Author(s):  
Julia Villalva ◽  
Belén Nieto-Ortega ◽  
Manuel Melle-Franco ◽  
Emilio Pérez
Keyword(s):  
Density Functional ◽  
Close Contact ◽  
Tight Binding ◽  
Energetic Cost ◽  
Molecular Fragments ◽  
Activation Barriers ◽  
Flat Surfaces ◽  
Different Types ◽  
Atomically Flat ◽  
Derivatives Of

The motion of molecular fragments in close contact with atomically flat surfaces is still not fully understood. Does a more favourable interaction imply a larger barrier towards motion even if there are no obvious minima? Here, we use mechanically interlocked rotaxane-type derivatives of SWNTs (MINTs) featuring four different types of macrocycles with significantly different affinities for the SWNT thread as models to study this problem. Using molecular dynamics, we find that there is no direct correlation between the interaction energy of the macrocycle with the SWNT and its ability to move along or around it. Density functional tight-binding calculations reveal small (<2.5 Kcal·mol-1) activation barriers, the height of which correlates with the commensurability of the aromatic moieties in the macrocycle with the SWNT. Our results show that macrocycles in MINTs rotate and translate freely around and along SWNTs at room temperature, with an energetic cost lower than the rotation around the C−C bond in ethane.<br>

Communication: Photoinduced Carbon Dioxide Binding with Surface-Functionalized Silicon Quantum Dots

2018 ◽  
Author(s):  
Oscar A. Douglas-Gallardo ◽  
Cristián Gabriel Sánchez ◽  
Esteban Vöhringer-Martinez
Keyword(s):  
Carbon Dioxide ◽  
Quantum Dots ◽  
Atmospheric Carbon Dioxide ◽  
Density Functional ◽  
Tight Binding ◽  
Carbon Dioxide Concentration ◽  
Research Area ◽  
Silicon Quantum Dots ◽  
Dependent Model ◽  
Photoinduced Charge

<div> <div> <div> <p>Nowadays, the search of efficient methods able to reduce the high atmospheric carbon dioxide concentration has turned into a very dynamic research area. Several environmental problems have been closely associated with the high atmospheric level of this greenhouse gas. Here, a novel system based on the use of surface-functionalized silicon quantum dots (sf -SiQDs) is theoretically proposed as a versatile device to bind carbon dioxide. Within this approach, carbon dioxide trapping is modulated by a photoinduced charge redistribution between the capping molecule and the silicon quantum dots (SiQDs). Chemical and electronic properties of the proposed SiQDs have been studied with Density Functional Theory (DFT) and Density Functional Tight-Binding (DFTB) approach along with a Time-Dependent model based on the DFTB (TD-DFTB) framework. To the best of our knowledge, this is the first report that proposes and explores the potential application of a versatile and friendly device based on the use of sf -SiQDs for photochemically activated carbon dioxide fixation. </p> </div> </div> </div>

Sign in / Sign up

Export Citation Format

Share Document