Coherent potential approximation

About: Coherent potential approximation is a research topic. Over the lifetime, 1930 publications have been published within this topic receiving 36805 citations.

Connection between the short-range order and the position of the fermi level on the density-of-states curve in the coherent potential approximation

Abstract: In the coherent potential approximation, the densities of electron states of binary alloys of transition elements with short-range order are obtained. These calculations are used to determine the contribution of the band-structure energy to the configuration part of the total energy, and the equilibrium values of the order parameter are calculated on the first coordination sphere. In the majority of the considered systems, the signs found for the order parameters agree with the experimental data.

Evidence of random distribution of carbon impurities in oxygen sites of zinc oxide

Abstract: A density functional study of substitutional carbon impurities in ZnO-host matrix with 6.25 at. % was performed applying both the supercell method and the coherent potential approximation. The first of these methods assumes the spatially ordered arrangement of carbon impurities in oxygen sites, whereas the second one simulates the spatially disordered impurity substitution of oxygen sublattice. In conjunction with a theoretical part, the X-ray photoelectron spectra of pure and C-doped zinc oxide were measured. The mapping of the valence band of the carbon-loaded ZnO allows establishing the appearance of impurity C 2p electronic states on the valence band top. The experimental energy position of these impurity C 2p states is theoretically reproducing essentially better by the assumption about random distribution of carbon impurities in oxygen sublattice.

Electronic Structure of α-SiH

Abstract: Recent advances based on the coherent potential approximation and the potential well analogy suggest that, in spite of the great complexity of the potential felt by an electron moving in an amorphous semiconductor, the electronic structure of the latter possesses a certain universality. As a result (and to a first approximation) only a few parameters matter. The situation is analoguous to that of a crystalline semiconductor, where a single quantity — the effective mass — allows one to bypass the complexity of the crystalline potential.

A simple model for compound forming liquid alloy systems

Abstract: We discuss the resistivity, thermopower and Knight shift as a function of temperature and composition for a number of alkali-IV A metal alloys using the tight binding C.P.A. model. Elastic electronph0n0n interaction results in a strong temperature dependence of the electronic structure. The calculations support the experimental evidence of near localization of the electrons close to stoichiometric compositions in liquid LiPb, LiSn, NaSn, NaPb and LiGe. Recently the Knight shift and electronic transport properties of a number of liquid alkali metal-IV A metal alloys have been measured as a function of temperature and concentration (1,2). (These liquid alloys exhibit partial salt-like character.) The properties of these alloys show anomalous behaviour around the composition of compound formation: a sharp maximum in the resistivity and a sharp negative minimum in its temperature derivative, a distinct minimum in the Knight shift and a maximum in its temperature derivative. The thermopower changes sign at this concentration. We will show that these properties can be explained within a simple tight binding band model in the coherent potential approximation (C.P.A.). Short range chemical order is neglected. By including elastic electron-ph0n0n interaction we can simulate effects due to (increasing) thermal disorder in the liquid. Increasing thermal disorder leads to a broadening of the bands and a filling of the (pseudo) gap.