Tight-binding model and interactions scaling laws for silicon and germanium

Electro-optical properties of strained monolayer boron phosphide

In this paper, we use tight-binding approximation and linear response theory to study the electronic and optical properties of strained monolayer boron-phosphide (h-BP). Compared with the previous DFT study and adding on-site energy variation to the Hamiltonian, we propose a theoretical approach to investigate the strain effects on the electronic and optical properties of the h-BP. Applying tensile strain increases the gap while compressive strain reduces it as the maximum and minimum of the gap are 1.45 eV and 1.14 eV respectively and are related to the biaxial strain. Also, we investigate the optical conductivity and electron energy loss spectrum (EELS) of the pristine and strained h-BP. The absorption peak of the [Formula: see text] appears in energy about 4 eV but applying strain shifts the peak's energy. Optical properties of pristine h-BP are isotopic and biaxial strain preserves this isotropy, but uniaxial strain exerts anisotropic behavior in the system.

Hybridization-Switching Induced Mott Transition in ABO_{3} Perovskites

We propose the concept of a "hybridization-switching induced Mott transition" which is relevant to a broad class of ABO_{3} perovskite materials including BiNiO_{3} and PbCrO_{3} that feature extended 6s orbitals on the A-site cation (Bi or Pb), and a strong A-O covalency induced ligand hole. Using ab initio electronic structure and slave rotor theory calculations, we show that such systems exhibit a breathing phonon driven A-site to oxygen hybridization-wave instability which conspires with strong correlations on the B-site transition metal ion (Ni or Cr) to trigger a Mott insulating state. This class of systems is shown to undergo a pressure induced insulator to metal transition accompanied by a colossal volume collapse due to ligand hybridization switching.

A tight binding and [Formula: see text] study of monolayer stanene

Stanene is a single layer of tin atoms which has been discovered as an emerging material for quantum spin Hall related applications. In this paper, we present an accurate tight-binding model for single layer stanene near the Fermi level. We parameterized the onsite and hopping energies for the nearest, second nearest, and third nearest neighbor tight-binding method, both without and with spin orbital coupling. We derived the analytical solution for the [Formula: see text]and [Formula: see text] points and numerically investigated the buckling effect on the material electronic properties. In these points of the reciprocal space, we also discuss a corresponding [Formula: see text] description, obtaining the value of the [Formula: see text] parameters both analytically from the tight-binding ones, and numerically, fitting the ab-initio dispersion relations. Our models provide a foundation for large scale atomistic device transport calculations.

Band structure of hydrogenated Si nanosheets and nanotubes

The band structures of fully hydrogenated Si nanosheets and nanotubes are elucidated by the use of an empirical tight-binding model. The hydrogenated Si sheet is a semiconductor with an indirect band gap of about 2.2 eV. The symmetries of the wavefunctions allow us to explain the origin of the gap. We predict that, for certain chiralities, hydrogenated Si nanotubes represent a new type of semiconductor, one with coexisting direct and indirect gaps of exactly the same magnitude. This behavior is different from that governed by the Hamada rule established for non-hydrogenated carbon and silicon nanotubes. A comparison to the results of an ab initio calculation is made.

Orbitronics: the intrinsic orbital current in p-doped silicon

The spin Hall effect depends crucially on the intrinsic spin-orbit coupling of the energy band. Because of the smaller spin-orbit coupling in silicon, the spin Hall effect is expected to be much reduced. We show that an electric field in p-doped silicon can induce a dissipationless orbital current in a fashion reminiscent of the spin Hall effect. The vertex correction from impurity scattering vanishes and the effect is robust against disorder. The orbital Hall effect leads to accumulation of local orbital momentum at the edge of the sample, and can be detected by the Kerr effect.