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.

Evolution of the impurity band in a weakly doped, highly compensated semiconductor

Abstract: We study the evolution of the impurity band in a weakly doped semiconductor as a function of the concentration of dopants, $x$. We present disorder-averaged results for the density of states of a doped simple cubic lattice and compare them with the predictions of the coherent potential approximation (CPA). For randomly distributed impurities the agreement is good, although CPA misses some qualitative features. We find that if electron-electron interactions can be ignored, as is the case in the highly compensated limit, the impurity band is still a clearly distinct feature in the spectrum even for dopant concentrations as large as $x\ensuremath{\sim}0.10$.

Determination of spin-wave stiffness in the Fe-Si system using first-principles calculations

Abstract: The behavior of magnetic materials can be simulated at the macroscale using the micromagnetic model whose key parameters, such as exchange stiffness constants and magnetic anisotropies, can be derived from first-principles electronic structure calculations. In this work we employed the Korringa-Kohn-Rostoker (KKR) Green's function method with the coherent potential approximation (CPA) to investigate the dependence of the spin-wave stiffness on the Si concentration for the three magnetic phases of FeSi, namely A2, B2, and $\mathrm{D}{0}_{3}$. Based on the structural, magnetic, and electronic structure analysis using the KKR-CPA methodology, the changes in the spin-wave stiffness caused by the addition of Si are primarily governed by the variations in the electronic structure.

Fluorite-type phase of TiO 2 (co)-doped with (Co, Nb and Ru): first-principles calculations

Abstract: In this work, the effect of cobalt, niobium and ruthenium, as single and double impurities, on the structural, magnetic and electronic properties of titanium dioxide ( $${\mathrm{TiO}}_{2}$$ ) is investigated on the basis of the Korringa Kohn Rostoker (KKR) method in combination with the coherent potential approximation (CPA). The exchange-correlation term is addressed within the generalized gradient approximation (GGA). The densities of states demonstrate a clear development of half-metallic (HM) behaviour with high spin polarization at the Fermi level (up to 100%) for the case of doping with cobalt. Furthermore, co-doping (Nb, Ru) increases the Curie temperature of $${\mathrm{TiO}}_{2}$$ to the maximum values of 542 and 440 K reached for Nb and Ru co-doped $${\mathrm{TiCoO}}_{2}$$ , respectively. In these compounds, the super-exchange and double-exchange interaction mechanisms explain the stability of ferromagnetic (FM) and anti-ferromagnetic (AFM) orders. Our findings confirm that these new materials have an enhanced potential for spintronic devices.

An investigation of high entropy alloy conductivity using first-principles calculations

Abstract: The Kubo-Greenwood equation, in combination with the first-principles Korringa-Kohn-Rostoker Coherent Potential Approximation (KKR-CPA) can be used to calculate the DC residual resistivity of random alloys at T = 0 K. We implemented this method in a multiple scattering theory based ab initio package, MuST, and applied it to the ab initio study of the residual resistivity of the high entropy alloy Al$_x$CoCrFeNi as a function of $x$. The calculated resistivities are compared with experimental data. We also predict the residual resistivity of refractory high entropy alloy MoNbTaV$_x$W. The calculated resistivity trends are also explained using theoretical arguments.

Coherent Potential Approximation Within the Exact Muffin-Tin Orbitals Theory

Abstract: An implementation of the coherent potential approximation (CPA) is carried out within the frameworks of the exact muffin-tin orbitals (EMTO) theory. During the self-consistent iterations the Poisson equation is solved using the spherical cell approximation, and the charge transfer between alloy components is treated within the screened impurity model. The total energy is calculated using the full charge density (FCD) technique. The FCD-EMTO-CPA method is suitable for accurate determination of the electronic structure and total energy of completely random alloys with a substi-tutional disorder on any kind of underlying crystal lattice. The accuracy of the method is demonstrated through test calculations performed on face centered cubic (fcc), body centered cubic (bcc), and hexagonal close packed (hcp) Cu-Zn binary alloys.