نتایج جستجو برای: tight binding method
تعداد نتایج: 2050197 فیلتر نتایج به سال:
In this research, we have investigated the effect of increasing length on the electronic transport of an armchair graphene nano-ribbons with nitrogen atom impurity and without impurity. The semi-infinite, one-dimensional molecular systems are connected to two electrodes and the electron-electron interaction is ignored. The system is described by a simple tight binding model. All calculations ar...
In the present paper, we calculate the effect of disorder on the density of states and localization of eigenstates of zigzag and armchair nano-ribbons. Both Anderson disorder model and quantom percolation are considered. The eigenstates of the disordered hamiltonian is calculated in a tight–binding approximation and the localization of eigenstates are characterized using the inverse participati...
in this research we have studied the effect of some transition-metals (cu, ag and au) substitutions on two-electron reduction potential of flavins by application of dft method. all geometries have been optimized at blyp level of theory and “6-31+g** + lanl2dz” mixed basis set. the frequency job at the same method and basis sets has been performed to obtain gibbs free energy of compounds. it h...
Empirical tight binding has proven to be very popular in recent years on account of its computational efficiency and accuracy. However, it has limitations, notably the difficulties associated with fitting parameters and improving models when the desired accuracy cannot be achieved. In the light of this, a number of efforts have been made to derive tight-binding models from first principles. Her...
The electrical properties and rectification behavior of the graphene self-switching diodes by side gates doping with nitrogen and boron atoms were investigated using density functional tight-binding method. The devices gates doping changes the electrical conductivity of the side gates and the semiconductor channel nanoribbons. As a result, the threshold voltage value under the forward bias is s...
This paper reviews the basic principles of the density-functional tight-binding (DFTB) method, which is based on density-functional theory as formulated by Hohenberg, Kohn and Sham (KS-DFT). DFTB consists of a series of models that are derived from a Taylor series expansion of the KS-DFT total energy. In the lowest order (DFTB1), densities and potentials are written as superpositions of atomic ...
We introduce a systematic method for constructing a class of lattice structures that we call “partial line graph”s. In tight-binding models on partial line graphs, energy bands with flat energy dispersions emerge. This method can be applied to twoand three-dimensional systems. We show examples of partial line graphs of square and cubic lattices. The method is useful in providing a guideline for...
PACS. 71.20.-b – Electron density of states and band structure of crystalline solids. Abstract. – We perform an orthogonal basis tight binding fit to an LAPW calculation of paramagnetic NaxCoO2 for several dopings. The optimal position of the apical oxygen at each doping is resolved, revealing a non-trivial dependence of the band structure and Fermi surface on oxygen height. We find that the sm...
The energy spectrum and eigenstates of single-layer black phosphorous nanoribbons in the presence of perpendicular magnetic field and in-plane transverse electric field are investigated by means of a tight-binding method and the effect of different types of edges is analytically examined. A description based on a new continuous model is proposed by expansion of the tight-binding model in the lo...
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