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.

Short-range order in a steady state of irradiated Cu-Pd alloys: comparison with fluctuations at thermal equilibrium

Abstract: The equilibrium short-range order (SRO) in Cu-Pd alloys is studied theoretically. The evolution of the Fermi surface-related splitting of the (110) diffuse intensity peak with changing temperature is examined. The results are compared with experimental observations for electron-irradiated samples in a steady state, for which the temperature dependence of the splitting was previously found in the composition range from 20 to 28 at.% Pd. The equilibrium state is studied by analysing available experimental and theoretical results and using a recently proposed alpha-expansion theory of SRO which is able to describe the temperature-dependent splitting. It is found that the electronic structure calculations in the framework of the Korringa-Kohn-Rostoker coherent potential approximation overestimate the experimental peak splitting. This discrepancy is attributed to the shift of the intensity peaks with respect to the positions of the corresponding reciprocal-space minima of the effective interatomic interaction towards the (110) and equivalent positions. Combined with an assumption about monotonicity of the temperature behaviour of the splitting, such a shift implies an increase of the splitting with increasing temperature for all compositions considered in this study. The alpha-expansion calculations seem to confirm this conclusion.

A calculation of magnetic properties of Fe3Pt alloys

Abstract: Densities of states of disordered and ordered ferromagnetic Fe3Pt alloys are calculated in the tight-binding d-band model with intra-atomic Coulomb interaction by making use of the coherent potential approximation for disordered alloys and the recursion method for ordered alloys. Magnetic properties such as the magnetisation, local magnetic moments low-temperature specific heat coefficient and spontaneous volume striction are calculated and compared with experiment. It is found that both the ordered and disordered Fe3Pt alloys are strong ferromagnets and that the ground-state properties can be explained by the Hartree-Fock approximation.

Surface segregation effect for transition-metal alloys in the coherent-potential approximation: general considerations and calculations for Cu-Ni alloys

Abstract: The surface segregation is calculated in the coherent-potential approximation. The influence of the surface potential, d-band fillings and d-level splitting of alloys components on the segregation is examined for a model density of states. The realistic tight-binding Hamiltonian is used to calculate the segregation for Cu-Ni alloys. The model for all reasonable values of parameters predicts the segregation of copper for all alloy compositions.

Cluster Theory of a Dilute Antiferromagnet. Application to the Mn1-cZncF2 System

Abstract: A cluster theory of a dilute antiferromagnet which simultaneously takes into account the fluctuations in the longitudinal and transverse part of the exchange interaction is proposed. The present theory allows to describe the dependence of the line shapes of the spin excitation spectrum on the nonmagnetic atom concentration and the wave vector. A comparison with experimental results indicates that the predictions of the theory are valid in a wide range of concentrations when the long-range order persists. It is pointed out that the coherent wave approximation accounts for the gross behaviour of the spin excitation spectrum. It is demonstrated that the results of the cluster theory are close to those of the coherent potential approximation, but more transparent and more suitable for comparison with experiment. [Russian Text Ignored.]

Systems of particles with random mass

Abstract: The kinetic and spectral properties of systems with random mass are considered. The conductivity sigma 0 of an electron gas with random effective mass is calculated in the coherent potential approximation. The authors show that the low-lying long-wave excitations of this system are described by the non-linear matrix sigma -model. The density of states of a two-dimensional electron gas with random mass in a perpendicular strong magnetic field is calculated.