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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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01 Sep 2009
TL;DR: In this article, the propagation of the acoustic wave in quasi-isotropic metamaterials is considered and the dispersion of effective stiffness and density is calculated by coherent potential approximation.
Abstract: Propagating of the acoustic wave in quasi-isotropic metamaterial is considered. The composite is consisted of an isotropic background material and embedded resonators in it. The frequency of the wave is taken that the wavelength is much longer that size of inclusions and distance between them. Dispersion of effective stiffness and density is calculated by coherent potential approximation. Zones where parameters reach negative values are estimated. Dispersion for the surface acoustic wave at the interface between metamaterial and “normal” matrial is calculated.
TL;DR: In this paper, a cluster expansion is used to predict the fcc groutnd states, i.e., the stable phases at zero Kelvin as a function of composition, for alloy systems.
Abstract: A cluster expansion is used to predict the fcc groutnd states, i.e., the stable phases at zero Kelvin as a function of composition, for alloy systems. TFile internetallic structures are not assumed, but derived rigorously by minimizing the configurational energy subject to linear constraints. This ground state search includes pair and multiplet interactions which spatially extend to fourth nearest neighbor. A large number of these concentration-independent interactions are computed by the method of direct configurational averaging using a linearizedmuffin- tin orbital Hamiltonian cast into tight binding form (TB-LMTO). The interactions, derived without the use of any adjustable or experimentally obtained parameters, are compared to those calculated via the generalized perturbation method extention of the coherent potential approximation within the context of a KKR Hamiltonian (KKR-CPA-GPM). Agreement with the KKR-CPA-GPM results is quite excellent, as is the comparison of the ground state results with the fcc-based portions of the experimentally-determined phase diagrams under consideration.
TL;DR: In this paper, the relativistic effects on electron transport in spin-polarized metals and random alloys on ab initio level using the TB-LMTO method were investigated.
TL;DR: In this paper, a new first-principles approach based on special quasi random structures and itinerant coherent potential approximation to compute the phonon spectra of disordered alloys is proposed and applied to Ni$_{0.5}$Pt${0.1}$ alloy.
Abstract: The lattice dynamics in substitutional disordered alloys with constituents having large size differences is driven by strong disorder in masses, inter-atomic force constants and local environments. In this letter, a new first-principles approach based on special quasi random structures and itinerant coherent potential approximation to compute the phonon spectra of such alloys is proposed and applied to Ni$_{0.5}$Pt$_{0.5}$ alloy. The agreement between our results with the experiments is found to be much better than for previous models of disorder due to an accurate treatment of the interplay of inter-atomic forces among various pairs of chemical species. This new formalism serves as a potential solution to the longstanding problem of a proper microscopic understanding of lattice dynamical behavior of disordered alloys.
TL;DR: In this paper, the interplay between electronic structure properties, crystalline effects and local chemical order is investigated for Ni-Al, Ni-Ti and Cu-Zn alloys.
Abstract: We show that the interplay between electronic structure properties, crystalline effects and local chemical order is quite distinct for Ni-Al, Ni-Ti and Cu-Zn, although they all exhibit a first order displacive transformation upon cooling from a high temperature partially ordered B2 phase. For this purpose, electronic structure and phase stability properties of these three alloys are investigated with a first principles approach. The study is based upon the Generalized Perturbation Method applied to the Korringa-Kohn-Rostoker multiple scattering description of the Coherent Potential Approximation, and temperature effects are taken into account within a generalized mean field approach.