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 study of the strained monolayer superlattices (Si)1/(Si1−xGex)1 (100)

Abstract: Electronic structures of strained monolayer superlattices (Si)1/(Si1−xGex)1 are calculated within the tight‐binding scheme by taking into consideration the effect of stress on atomic interactions. Gap variations with composition and band offsets for different strain conditions are obtained. When Si(Ge) is grown on cubic Ge(Si) with stress to match the lattice constant of the substrates, the calculated nonmonotonic behavior of the superlattice Eg(x) curve can be attributed to a similar phenomenon of the bulk alloy under the same strain. The energy band of the monolayer Si/Ge shows the zinc blende symmetry with a Si‐like feature. Starting with the virtual crystal approximation for the calculation of gap and density of states, it is found that further modification using coherent potential approximation is not very significant.

Orbital-based charge self-consistent Blackman-Esterling-Berk coherent potential approximation approach to substitutional disorder within a pseudopotential framework

Abstract: We report the development of an ab initio electronic structure method applicable to generic substitutionally disordered real materials. A charge self-consistent orbital-based extension of the coherent potential approximation due to Blackman, Esterling, and Berk (BEB-CPA) is combined with the mixed-basis pseudopotential density functional theory approach. The general formalism in terms of a nonorthogonal basis set including subtleties of the pseudopotential framework is outlined. The BEB-CPA is validated on a binary tight-binding toy model against exact diagonalization of a randomly occupied cluster. Finally, the developed ab initio approach is benchmarked for a binary CuZn alloy, which confirms the robustness of the charge self-consistent procedure with respect to initial conditions.

Effects of impurities on the magnetic property in copper oxides

Abstract: We study effects of the nonmagnetic impurities on the magnetic property in the CuO 2 plane of copper oxides. We calculate the spin susceptibility in the normal state, for the CuO 2 plane with nonmagnetic impurities substituted for Cu atoms, on the basis of the d–p model. We take account of the impurity scattering and the Coulomb interaction at each Cu site within the single-site coherent potential approximation and the fluctuation-exchange approximation, respectively. Our result implies that the nonmagnetic impurities suppress the antiferromagnetic spin fluctuations which mediate the superconductivity in high-temperature superconductors.

Electronic properties of b.c.c. transition metal solid solutions. a study of the Nr-Nb system

Abstract: Calculations of electron densities of states and of soft—X-ray absorption spectra in Zr−Nb alloys have been performed in the frame of the coherent potential approximation in its multiple-scattering version (KKR-CAP). It is shown that a lot of care is needed in applying the simple rigid-band model to these systems, in order to explain experimental data. Results are also diseussed in connection with existing experimental data and good agreement is found.

Generalized two-body self-consistent theory of random linear dielectric composites: an effective-medium approach to clustering in highly-disordered media

Abstract: Effects of two-body dipolar interactions on the effective permittivity/conductivity of a binary, symmetric, random dielectric composite are investigated in a self-consistent framework. By arbitrarily splitting the singularity of the Green tensor of the electric field, we introduce an additional degree of freedom into the problem, in the form of an unknown "inner" depolarization constant. Two coupled self-consistent equations determine the latter and the permittivity in terms of the dielectric contrast and the volume fractions. One of them generalizes the usual Coherent Potential condition to many-body interactions between single-phase clusters of polarizable matter elements, while the other one determines the effective medium in which clusters are embedded. The latter is in general different from the overall permittivity. The proposed approach allows for many-body corrections to the Bruggeman-Landauer (BL) scheme to be handled in a multiple-scattering framework. Four parameters are used to adjust the degree of self-consistency and to characterize clusters in a schematic geometrical way. Given these parameters, the resulting theory is "exact" to second order in the volume fractions. For suitable parameter values, reasonable to excellent agreement is found between theory and simulations of random-resistor networks and pixelwise-disordered arrays in two and tree dimensions, over the whole range of volume fractions. Comparisons with simulation data are made using an "effective" scalar depolarization constant that constitutes a very sensitive indicator of deviations from the BL theory.