Tight-binding calculation of the optical conductivity in NaxCoO2

2004 ◽  
Vol 132 (1) ◽  
pp. 43-47 ◽  
Author(s):  
T. Sugibayashi ◽  
D.S. Hirashima
Keyword(s):  
Optical Conductivity ◽  
Tight Binding

Electronic Properties of Liquid Silicon

1985 ◽  
Vol 63 ◽  
Author(s):  
J. Q. Broughton ◽  
P. B. Allen
Keyword(s):  
Molecular Dynamics ◽  
Fermi Level ◽  
Electronic Properties ◽  
Density Of States ◽  
Optical Conductivity ◽  
Tight Binding ◽  
Liquid Silicon ◽  
Binding Parameters ◽  
Simple Cubic ◽  
Weber Potential

ABSTRACTThe electronic properties of liquid silicon were computed by coupling molecular dynamics and tight binding methods. By employing the Stillinger-Weber potential, atomic configurations of liquid Si at 1740°C were generated by molecular dynamics. Tight binding parameters chosen to fit fcc,bcc, simple cubic and diamond cubic band structures of silicon, were then used to obtain the electronic properties of the system. All states within 10eV of the Fermi level are found to be delocalized, the density of states spectrum similar (but much broadened) to that of diamond cubic silicon and the optical conductivity is found to be almost featureless with no Drude behavior.

OPTICAL CONDUCTIVITY OF TWO-DIMENSIONAL LATTICE

2008 ◽  
Vol 22 (06) ◽  
pp. 435-445 ◽  
Author(s):  
LEI XU ◽  
JUN ZHANG
Keyword(s):  
Optical Conductivity ◽  
Tight Binding ◽  
Two Dimensional ◽  
Energy Bands ◽  
Electron Model ◽  
Dimensional Lattice ◽  
Flux Parameter ◽  
Drude Weight ◽  
The Mean ◽  
Mean Kinetic Energy

We investigate the optical conductivity in the two-dimensional (2D) square and triangular tight-binding lattice-electron model with staggered magnetic flux (SMF). The SMF results in a two-sublattice system with two branches of energy bands in both cases, and even generates new flux-dependent optical properties. Results for the flux parameter dependence of the mean kinetic energy, the Drude weight and the optical conductivity are discussed in detail. A comparison between the two cases has been done.

scholarly journals Optical signatures of multifold fermions in the chiral topological semimetal CoSi

2020 ◽  
Vol 117 (44) ◽  
pp. 27104-27110 ◽  
Author(s):  
Bing Xu ◽  
Zhenyao Fang ◽  
Miguel-Ángel Sánchez-Martínez ◽  
Jorn W. F. Venderbos ◽  
Zhuoliang Ni ◽  
...  
Keyword(s):  
Optical Conductivity ◽  
Chemical Potential ◽  
Tight Binding ◽  
Low Frequency ◽  
Optical Response ◽  
Flat Band ◽  
Fermi Velocity ◽  
Topological Semimetal ◽  
Different Types ◽  
Topological Semimetals

We report the optical conductivity in high-quality crystals of the chiral topological semimetal CoSi, which hosts exotic quasiparticles known as multifold fermions. We find that the optical response is separated into several distinct regions as a function of frequency, each dominated by different types of quasiparticles. The low-frequency intraband response is captured by a narrow Drude peak from a high-mobility electron pocket of double Weyl quasiparticles, and the temperature dependence of the spectral weight is consistent with its Fermi velocity. By subtracting the low-frequency sharp Drude and phonon peaks at low temperatures, we reveal two intermediate quasilinear interband contributions separated by a kink at 0.2 eV. Using Wannier tight-binding models based on first-principle calculations, we link the optical conductivity above and below 0.2 eV to interband transitions near the double Weyl fermion and a threefold fermion, respectively. We analyze and determine the chemical potential relative to the energy of the threefold fermion, revealing the importance of transitions between a linearly dispersing band and a flat band. More strikingly, below 0.1 eV our data are best explained if spin-orbit coupling is included, suggesting that at these energies, the optical response is governed by transitions between a previously unobserved fourfold spin-3/2 node and a Weyl node. Our comprehensive combined experimental and theoretical study provides a way to resolve different types of multifold fermions in CoSi at different energy. More broadly, our results provide the necessary basis to interpret the burgeoning set of optical and transport experiments in chiral topological semimetals.

Electrical and optical conductivities of bilayer silicene: Tight-binding calculations

2017 ◽  
Vol 31 (22) ◽  
pp. 1750158 ◽  
Author(s):  
Raad Chegel ◽  
Azra Feyzi ◽  
Rostam Moradian
Keyword(s):  
Electrical Conductivity ◽  
Electric Field ◽  
Optical Conductivity ◽  
Energy Gap ◽  
Integral Formula ◽  
Tight Binding ◽  
Tight Binding Approximation ◽  
Conductivity Increase ◽  
Energy Formula ◽  
Effects Of Temperature

The electronic structures, densities of state and electrical and optical conductivities of monolayer and bilayer silicene sheets are investigated using tight-binding approximation and Green’s function method. We found that applying the electric field on doped bilayer silicene leads to band structure modification. For AA-stacked bilayer silicene, applying and increasing the bias [Formula: see text] does not create the energy gap but for AB-stacked bilayer, a small bias [Formula: see text] is enough to create an energy gap. It is shown that the electrical conductivity depends on temperature, doping and electric field. In pristine and doped AA- and AB-stacked bilayers, electrical conductivity increases (decreases) linearly with [Formula: see text] at low (high) temperature and decreases by increasing the doping onsite energy [Formula: see text] at all [Formula: see text] ranges. The effects of temperature on the conductivity increase with the increase of electric field. It is found that the electrical conductivity depends on the amount of interlayer hopping integral [Formula: see text]. For the case of AA-stacking, there are three steps in optical conductivity at energies [Formula: see text] and [Formula: see text] for [Formula: see text] and [Formula: see text]. For the case of AB-stacking the optical conductivity has a step at [Formula: see text] similar to monolayer sheet and some steps at energies [Formula: see text].

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