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.

Tight-binding coherent-potential approximation including off-diagonal disorder.

Abstract: We present a generalization of the tight-binding coherent-potential approximation (TB-CPA) to substitutionally disordered alloys with both diagonal and off-diagonal disorder (ODD), taking into account all relevant {ital s}, {ital p}, and {ital d}, orbitals. This generalization is based on the work of Blackman, Esterling, and Berk (Phys. Rev. B 4, 2412 (1971)) which treated ODD within a single-band model of a disordered alloy. The method is illustrated with calculations of the density of states of disordered Cu{sub 0.75}Pd{sub 0.25} alloys. We find that inclusion of ODD improves the agreement with specific-heat data, but it does not resolve a discrepancy with the results of first-principles, muffin-tin CPA calculations regarding the Pd component of the density of states.

Dependence of configurational interactions on concentration in Ni1-cCuc alloys

Abstract: Pair and triple configurational interactions in Ni1-cCuc alloys are calculated by the LMTO-ASA-CPA method. Strong dependence of these interactions on concentration connected with the crossing of the d-band edge by the Fermi level is revealed. General microscopic expressions for these interactions are discussed for the case when the electron-electron interaction terms are taken into account in the framework of the density functional method.

General theory for calculating disorder-averaged Green's function correlators within the coherent potential approximation

Abstract: We report a diagrammatic method to solve the general problem of calculating configurationally averaged Green's function correlators that appear in quantum transport theory for nanostructures containing disorder. The theory treats both equilibrium and nonequilibrium quantum statistics on an equal footing. Since random impurity scattering is a problem that cannot be solved exactly in a perturbative approach, we combine our diagrammatic method with the coherent potential approximation (CPA) so that a reliable closed-form solution can be obtained. Our theory not only ensures the internal consistency of the diagrams derived at different levels of the correlators but also satisfies a set of Ward-like identities that corroborate the conserving consistency of transport calculations within the formalism. The theory is applied to calculate the quantum transport properties such as average ac conductance and transmission moments of a disordered tight-binding model, and results are numerically verified to high precision by comparing to the exact solutions obtained from enumerating all possible disorder configurations. Our formalism can be employed to predict transport properties of a wide variety of physical systems where disorder scattering is important.

Coherent-potential approximation in the tight-binding linear muffin-tin orbital method.

Abstract: We describe a consistent approach for applying the coherent-potential approximation (CPA) to the various representations of the linear muffin-tin orbital method. Unlike the previous works of Kudrnovsky [ital et] [ital al]. [Phys. Rev. B 35, 2487 (1987); 41, 7515 (1990)], our results for the ensemble-averaged Green functions in the tight-binding representation yield [ital E]- and [bold r]-dependent quantities that are consistent with the traditional applications of the single-site CPA. To illustrate the reliability and the usefulness of our approach we compare the nonspherically averaged charge densities, calculated in real space, of ordered NiPt in [ital L]1[sub 0] structure and the substitutionally disordered Ni[sub 0.5]Pt[sub 0.5] on a face-centered-cubic lattice.