Hybridization in Electronic States and Optical Properties of Covalent Amorphous Semiconductors

1999 ◽  
Vol 588 ◽  
Author(s):  
Yuzo Shinozuka
Keyword(s):  
Optical Properties ◽  
Spatial Correlation ◽  
Nearest Neighbor ◽  
Tight Binding ◽  
Electronic States ◽  
Amorphous Semiconductors ◽  
Transfer Energy ◽  
Binding Model ◽  
Covalent Bonds ◽  
Conduction Bands

AbstractThe electronic structure and optical properties of covalent amorphous semiconductors are theoretically studied with special attention to the s-p hybridization in electronic states and the spatial correlation in their mixing. One-dimensional tight binding model is used in which the interatomic transfer energy of an electron between nearest neighbor atoms depends linearly on their interatomic distance. All the electronic states are numerically calculated for a 150-atom system and the ensemble average is taken over 10 samples. Following results have been obtained. As the degree of randomness increases, the degree of hybridization decreases and rearrangements in the covalent bonds take place. The width of the band gap decreases but the gap remains rather long compared to a case where the spatial correlation is neglected. There appears a characteristic peak in the optical absorption spectrum, which reflects central peaks in the partial (s- or p-) density of states in the valence and conduction bands and is related to an electron localization caused by the spatial correlation.

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.

Electronic modes in carbon nanotubes with single and double impurity sites

2017 ◽  
Vol 31 (29) ◽  
pp. 1750220
Author(s):  
P. G. Komorowski ◽  
M. G. Cottam
Keyword(s):  
Carbon Nanotubes ◽  
Nearest Neighbor ◽  
Tight Binding ◽  
Longitudinal Axis ◽  
Binding Model ◽  
Substitutional Impurity ◽  
Impurity Atoms ◽  
Spatial Configurations ◽  
Impurity Sites ◽  
Walled Carbon Nanotubes

A theoretical study of isolated and doubly-clustered impurities is presented for the electronic excitations in a carbon nanotube lattice. Using a matrix operator formalism and a tight-binding model where the interactions between atoms take place via nearest-neighbor hopping, the properties of the excitations are deduced. A geometry consisting of long, single-walled carbon nanotubes is assumed with the defects introduced in the form of substitutional impurity atoms, giving rise to the localized electronic modes of the nanotube as well as the propagating modes of the pure (host) material. The impurities are assumed to be in a low concentration, having the form of either a single, isolated defect or a small cluster of two defects close together. A tridiagonal matrix technique is employed within a Green’s function formalism to obtain the properties of the discrete modes of the system, including their frequencies and localization. The numerical examples show a dependence on the nanotube diameters and on the relative spatial configurations of the impurities. The results contrast with the previous studies of line impurities since there is no translational symmetry along the longitudinal axis of the nanotubes in the present case.

scholarly journals Evidence for orbital order and its relation to superconductivity in FeSe0.4Te0.6

2015 ◽  
Vol 1 (9) ◽  
pp. e1500206 ◽  
Author(s):  
Udai R. Singh ◽  
Seth C. White ◽  
Stefan Schmaus ◽  
Vladimir Tsurkan ◽  
Alois Loidl ◽  
...  
Keyword(s):  
Structural Phase ◽  
Tight Binding ◽  
Electronic States ◽  
Orbital Ordering ◽  
Binding Model ◽  
Quasi Particle ◽  
Iron Based Superconductors ◽  
Iron Chalcogenide ◽  
Correlated Electron ◽  
Iron Based

The emergence of nematic electronic states accompanied by a structural phase transition is a recurring theme in many correlated electron materials, including the high-temperature copper oxide– and iron-based superconductors. We provide evidence for nematic electronic states in the iron-chalcogenide superconductor FeSe0.4Te0.6 from quasi-particle scattering detected in spectroscopic maps. The symmetry-breaking states persist above Tc into the normal state. We interpret the scattering patterns by comparison with quasi-particle interference patterns obtained from a tight-binding model, accounting for orbital ordering. The relation to superconductivity and the influence on the coherence length are discussed.

Electronic States of BCN Alloy Nanotubes in a Simple Tight-Binding Model

2003 ◽  
Vol 72 (10) ◽  
pp. 2656-2664 ◽  
Author(s):  
Tomoaki Yoshioka ◽  
Hidekatsu Suzuura ◽  
Tsuneya Ando
Keyword(s):  
Tight Binding ◽  
Electronic States ◽  
Tight Binding Model ◽  
Binding Model
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