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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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TL;DR: In this article , the authors describe implementation and analysis of a first-principles theory for the leading terms in an expansion of a Gibbs free energy of a multi-component alloy in terms of order parameters.
Abstract: We describe implementation and analysis of a first-principles theory, derived in an earlier work, for the leading terms in an expansion of a Gibbs free energy of a multi-component alloy in terms of order parameters that characterize potential, compositional phases. The theory includes effects of rearranging charge and other electronics from changing atomic occupancies on lattice sites. As well as the rigorous description of atomic short-range order in the homogeneously disordered phase, pairwise interaction parameters suited for atomistic modelling in a multicomponent setting can be calculated. From our study of an indicative series of the Cantor-Wu alloys, NiCo, NiCoCr, NiCoFeCr, and NiCoFeMnCr, we find that the interactions are not approximated well either as pseudobinary or restricted to nearest neighbour range. Our computed order-disorder transition temperatures are low, consistent with experimental observations, and the nature of the ordering is dominated by correlations between Ni, Co, and Cr, while Fe and Mn interact weakly. Further atomistic modelling suggests that there is no true single-phase low-temperature ground state for these multicomponent systems. Instead the single-phase solid solution is kept stable to low temperatures by the large configurational entropy and the Fe, Mn dilution effects. The computationally cost-effectiveness of our method makes it a good candidate for further exploration of the space of multicomponent alloys.

5 citations

Journal ArticleDOI
01 Mar 2011
TL;DR: In this paper, the non-local coherent potential approximation (NL-CPA) was extended to materials with multi-atom per unit cell lattices. And the method is described using a Green function formalism and illustrated by an implementation for a simplified one-dimensional tight binding model with substitutional disorder.
Abstract: Over the last few years the Non-Local Coherent Potential Approximation (NL-CPA) has been shown to provide an effective way to describe the electronic structure and related properties of disordered systems, where short-range order (SRO) and other local environment effects are important. Here we present its generalization to materials with multi-atom per unit cell lattices. The method is described using a Green function formalism and illustrated by an implementation for a simplified one-dimensional tight-binding model with substitutional disorder. This development paves the way for a natural reimplementation of the Korringa-Kohn-Rostoker (KKR) multiple scattering solution of Kohn-Sham equations for ab-initio calculations of real materials.

5 citations

01 Jan 2002
Abstract: The Coherent Potential Approximation (CPA) method [1] is a powerful analytical technique for calculations of density of states ρ(ω) for binary alloys AxB1−x. Not only is density of states obtained but also so called coherent potential can be extracted from the calculations, and used in further studies. In this example we apply it to get the residual resistivity in alloys. Before we proceed with the presentation of the CPA methods, some comments on the applicability or restrictions of this technique are necessary. The two components of the alloy, elements A and B, must be expressed in terms of the same starting densities ρ0(ω). This means, that we have to have the same bandwidth of A and B elements. Therefore compounds composed of two transition metals, such as FexV1−x alloy, are acceptable, while, for example, a transition metal and a rare earth compound would not be treatable correctly in the CPA, because the bandwidth of f -electrons of the rare earth elements is very narrow. The CPA is a one electron approximation, and any corrections due to electronelectron correlations, or interaction of electrons with the lattice etc., may only be incorporated by a suitable modification of the density of states of pure elements which is the input information for the CPA method. Also, within the CPA we do not get the

5 citations

Journal ArticleDOI
TL;DR: Using the all-electron fully relativistic Karringa-Kohn-Rostoker coherent-potential-approximation method self-consistent total-energy calculations were performed for the system Au/Pd, an interesting quantitative comparison for the alloy total energies, spectral densities, and properties related to the Fermi energy or FermI surface can be presented.
Abstract: Using the all-electron fully relativistic Karringa-Kohn-Rostoker coherent-potential-approximation method self-consistent total-energy calculations were performed for the system Au/Pd. The calculated equilibrium lattice constants are in fairly good agreement with the experimental data. In particular, microscopic reasons for the breaks in the variation of the lattice constants with concentration can be derived from the results. Since the calculations were carried out self-consistently for a maximum angular momentum quantum number of 2 as well as 3, an interesting quantitative comparison for the alloy total energies, spectral densities, and properties related to the Fermi energy or Fermi surface can be presented.

5 citations

Journal ArticleDOI
TL;DR: In this paper, a coherent potential approximation for insulating antiferromagnetic alloys is presented, in which the off-diagonal (transfer) parts of the exchange interaction are treated on the same basis as the diagonal parts.
Abstract: A coherent potential approximation for insulating antiferromagnetic alloys is presented, in which the off-diagonal (transfer) parts of the exchange interaction are treated on the same basis as the diagonal parts. The theory uses three parameters which are adjusted to ensure no net scattering on average from a nearest-neighbour pair of atoms when immersed in the coherent crystal. This type of treatment is especially suitable for Heisenberg exchange where the diagonal and off-diagonal terms have the same magnitudes. Results are presented for the one-magnon densities of states at various concentrations for the systems K(Mn, Ni)F3, K(Ni, Zn)F3 and K2(Mn, Ni)F4.

5 citations


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Performance
Metrics
No. of papers in the topic in previous years
YearPapers
20234
202222
202127
202030
201930
201840