Topic
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.
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TL;DR: In this article, a coherent-potential approximation for obtaining the electronic density of states and component charge densities in disordered muffin-tin alloys is presented. Butler et al. showed that self-consistency in treating disorder influences the electronic spectrum.
Abstract: I report implementation of the coherent-potential approximation for obtaining the electronic density of states and component charge densities in disordered muffin-tin alloys. Illustrative results for ${\mathrm{Cu}}_{x}{\mathrm{Ni}}_{1\ensuremath{-}x}$ are presented. The extent to which the self-consistency in treating disorder influences the electronic spectrum is considered.
33 citations
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TL;DR: In this paper, the evolution of the electronic structure of titanium dioxide TiO2 − δ (rutile) with the growth of nonstoichiometry in the oxygen sublattice was studied.
Abstract: We formulate and implement a method for electronic structure calculations based on the coherent potential approximation. This method provides an accurate description for nonstoichiometric compounds with the disordered location of vacancies. In the essence of its formulation, the method is similar to the implementation of the local electron density approximation in combination with the dynamical mean field theory (LDA + DMFT) and, hence, it can be easily incorporated in the latter approach. We study the evolution of the electronic structure of titanium dioxide TiO2 − δ (rutile) with the growth of nonstoichiometry in the oxygen sublattice. The results of the calculations are compared to the experimental data on the photoemission spectra.
33 citations
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TL;DR: In this article, the intrinsic magnetic properties of the compounds YCo5 and GdCo5, members of the RETM5 class of permanent magnets, were investigated through calculations based on a Green's function formulation of density-functional theory, treating the thermal disorder of the local magnetic moments within the coherent potential approximation.
Abstract: We present an investigation into the intrinsic magnetic properties of the compounds YCo5 and GdCo5, members of the RETM5 class of permanent magnets (RE = rare earth, TM = transition metal). Focusing on Y and Gd provides direct insight into both the TM magnetization and RE-TM interactions without the complication of strong crystal field effects. We synthesize single crystals of YCo5 and GdCo5 using the optical floating zone technique and measure the magnetization from liquid helium temperatures up to 800 K. These measurements are interpreted through calculations based on a Green’s function formulation of density-functional theory, treating the thermal disorder of the local magnetic moments within the coherent potential approximation. The rise in magnetization with temperature of GdCo5 is shown to arise from a faster disordering of the Gd magnetic moments compared to the antiferromagnetically-aligned Co sublattice. We use the calculations to analyze the different Curie temperatures of the compounds and also compare the molecular (Weiss) fields at the RE site with previously-published neutron scattering experiments. To gain further insight into the RE-TM interaction we perform substitutional doping on the TM site, studying the compounds RECo4.5Ni0.5, RECo4Ni and RECo4.5Fe0.5. Both our calculations and experiments on powdered samples find an increased/decreased magnetization with Fe/Ni-doping respectively. The calculations further reveal a pronounced dependence on the location of the dopant atoms of both the Curie temperatures and the Weiss field at the RE site
33 citations
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TL;DR: A tight-binding version of the linear-muffin-tin-orbital method is used to describe the electronic structure of random overlayers on a perfect substrate in a self-consistent manner within the local-density approximation.
Abstract: A tight-binding version of the linear-muffin-tin-orbital method is used to describe the electronic structure of random overlayers on a perfect substrate in a self-consistent manner within the local-density approximation. The true semi-infinite nature of the system is incorporated via the surface-Green's-function approach. A generalization of the coherent-potential-approximation method to treat inhomogeneous alloys is used to study the effect of disorder. The formalism is applied to evaluate the layer-projected densities of states and work functions of random Ag-Pd overlayers on a fcc Ag(001) substrate.
33 citations
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TL;DR: The results clearly indicate that for disordered alloys any future implementation of a full-potential method within the single-site CPA should be carried out with charge-neutral cells rather than the Wigner-Seitz cells.
Abstract: Based on the idea of charge-neutral atoimc spheres we have calculated the electronic structure of ordered and disordered Cu-Zn, Ni-Pt, and Al-Li alloys using the linear-muffin-tin-orbital (LMTO) method and the Korringa-Kohn-Rostoker coherent potential approximation (KKR CPA) method in the atomic-sphere approximation (ASA), respectively. The equilibrium lattice constants and the formation energies of ordered alloys obtained with the LMTO-ASA method show that the calculations done with charge-neutral atomic spheres are closer to the experimental results than the conventional equivolume atomic-sphere-type calculations. In the case of disordered alloys, we find that charge-neutral atomic spheres are essential for the stability of these alloys within the KKR-ASA CPA method where the Madelung-type contribution is neglected. Our results clearly indicate that for disordered alloys any future implementation of a full-potential method within the single-site CPA should be carried out with charge-neutral cells rather than the Wigner-Seitz cells.
33 citations