Bandstructure Effects in Phosphorene Nanoribbon MOSFETs from NEGF Simulations Using a New DFT-based Tight-binding Hamiltonian Model

2021 ◽  
Author(s):  
Mirko Poljak ◽  
Mislav Matic
Keyword(s):  
Tight Binding ◽  
Hamiltonian Model

Dynamical impurity in a tight-binding Hamiltonian model

2001 ◽  
Vol 34 (29) ◽  
pp. 5795-5814 ◽  
Author(s):  
A Karina Chattah ◽  
Manuel O Cáceres
Keyword(s):  
Tight Binding ◽  
Hamiltonian Model

Universal description of heating-induced reshaping preference of core–shell bimetallic nanoparticles

Nanoscale ◽  
2019 ◽  
Vol 11 (3) ◽  
pp. 1386-1395 ◽  
Author(s):  
Zheng Zhao ◽  
Haoxiang Xu ◽  
Yi Gao ◽  
Daojian Cheng
Keyword(s):  
Theoretical Model ◽  
Surface Energy ◽  
Bimetallic Nanoparticles ◽  
Tight Binding ◽  
Atomic Scale ◽  
Core Shell ◽  
Molecular Dynamic Simulations ◽  
Dynamic Simulations ◽  
Atomic Size ◽  
Hamiltonian Model

To achieve universal description of the reshaping process of core–shell bimetallic nanoparticles, we combined the tight-binding Ising Hamiltonian model with molecular dynamic simulations to propose a general theoretical model at the atomic scale while considering the temperature, bond energy, atomic size, and surface energy effects.

scholarly journals Flake Electrical Conductivity of Few-Layer Graphene

2014 ◽  
Vol 2014 ◽  
pp. 1-6 ◽  
Author(s):  
Hamze Mousavi ◽  
Jabbar Khodadadi
Keyword(s):  
Electrical Conductivity ◽  
Small Deviation ◽  
Tight Binding ◽  
Single Layer ◽  
Function Technique ◽  
Kubo Formula ◽  
Layer Graphene ◽  
Linear Behavior ◽  
Hamiltonian Model ◽  
Few Layer Graphene

The Kubo formula for the electrical conductivity of per stratum of few-layer graphene, up to five, is analytically calculated in both simple and Bernal structures within the tight-binding Hamiltonian model and Green's function technique, compared with the single-layer one. The results show that, by increasing the layers of the graphene as well as the interlayer hopping of the nonhybridizedpzorbitals, this conductivity decreases. Although the change in its magnitude varies less as the layer number increases to beyond two,distinguishably, at low temperatures, it exhibits a small deviation from linear behavior. Moreover, the simple bilayer graphene represents more conductivity with respect to the Bernal case.

scholarly journals Mobility Edges in One-dimensional Disordered Aharonov-Bohm Rings

2019 ◽  
Vol 29 (4) ◽  
pp. 471
Author(s):  
Phi Ba Nguyen
Keyword(s):  
Tight Binding ◽  
System Size ◽  
Disorder Strength ◽  
Weak Disorder ◽  
Localization Transition ◽  
One Dimensional ◽  
Energy Disorder ◽  
Hamiltonian Model ◽  
Aharonov Bohm ◽  
Flux Energy

We study numerically the localization properties of the eigenstates of a tight-binding Hamiltonian model for noninteracting electrons moving in a one-dimensional disordered ring pierced by an Aharonov-Bohm flux. By analyzing the dependence of the inverse participation ratio on Aharonov-Bohm flux, energy, disorder strength and system size, we find that all states in the ring are delocalized in the weak disorder limit. The states lying deeply in the band tails will undergo a continuous delocalization-localization transition as the disorder strength in the ring sweeps from the weak to the strong disorder regime.

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>

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