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.

Random matrix theory for CPA: generalization of Wegner's n-orbital model

Abstract: We introduce a generalization of Wegner's (1979) n-orbital model for the description of randomly disordered systems by replacing his ensemble of Gaussian random matrices by an ensemble of randomly rotated matrices. We calculate the one- and two-particle Green functions and the conductivity exactly in the limit n to infinity . Our solution solves the coherent potential approximation equation of the (n=1) Anderson model for arbitrarily distributed disorder. We show how the Lloyd model is included in our model.

Disordered alloys with short-range order: A Korringa-Kohn-Rostoker formulation within the cluster coherent-potential approximation.

Abstract: We present a generalization of the Korringa-Kohn-Rostoker cluster coherent-potential approximation for systems with short-range order (SRO). For this purpose we have used the generalized augmentedspace formalism of Gray and Kaplan, in which one can deal with independent (corresponding to purely random systems) as well as dependent (corresponding to systems with SRO) random variables. The expression for the configuration-averaged Green's function in this case is essentially an expansion about the Green's function for a purely random system, and contains an infinite number of terms. For simplicity, we truncate the series after the second-order correction term

The electrical resistivity of the two-conduction-band heavy-fermion alloy system

Abstract: The electrical resistivity of the heavy-fermion alloys is calculated through a two-conduction-band slave boson model using the self-consistent coherent potential approximation method. The results indicate that for very low temperatures the resistivity of the alloy system follows the rho 0+AT2 law and the coefficient A changes from negative values to positive values as the alloy concentration increases. The occurrence of the resistivity maximum at a finite temperature is also obtained on increasing the concentration of heavy-fermion alloys.

Interband quantum kinetics with static disorder scattering I: Direct CPA solution for a rectangular-pulse-excited semiconductor

Abstract: For a two band model semiconductor alloy with the disorder potential concentrated to the conduction band, the photoexcitation by a long rectangular pulse represents a case soluble in the coherent potential approximation. Explicit analytic expressions for the transient electron distribution are derived using the nonequilibrium Green functions. The evanescent coherent component is gradually superseded by the incoherent distribution whose saturation value is obtained using the Ward identity.

First-principles description of phonons in Ni 50 Pt 50 disordered alloys: The role of relaxation

Abstract: Using a combination of density-functional perturbation theory and the itinerant coherent potential approximation, we study the effects of atomic relaxation on the inelastic incoherent neutron scattering cross sections of disordered Ni$_{50}$Pt$_{50}$ alloys. We build on previous work, where empirical force constants were adjusted {\it ad hoc} to agree with experiment. After first relaxing all structural parameters within the local-density approximation for ordered NiPt compounds, density-functional perturbation theory is then used to compute phonon spectra, densities of states, and the force constants. The resulting nearest-neighbor force constants are first compared to those of other ordered structures of different stoichiometry, and then used to generate the inelastic scattering cross sections within the itinerant coherent potential approximation. We find that structural relaxation substantially affects the computed force constants and resulting inelastic cross sections, and that the effect is much more pronounced in random alloys than in ordered alloys.