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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 effect of alloying in intermediate valence compounds is studied within an extended version of the Anderson model which takes into account substitutional disorder of the rare earth ions, and the authors concentrate on modifications of the conduction band, describe them by an effective shift in the Fermi energy, and consider its influence on the mixed valence behaviour.
Abstract: The effect of alloying in intermediate valence compounds is studied within an extended version of the Anderson model which takes into account substitutional disorder of the rare earth ions In particular, we concentrate on modifications of the conduction band, describe them by an effective shift in the Fermi energy, and consider its influence on the mixed valence behaviour By applying the alloy analog approximation to the manyparticle Hamiltonian describing the local magnetic 4f shells, the complete effective Hamiltonian is that of a ternary alloy This problem is solved within the coherent potential approximation and the static magnetic susceptibility is calculated as a function of temperature and disorder Depending on the shift of the Fermi energy with respect to the 4f levels, qualitatively different behaviour is obtained which corresponds very well with magnetic measurements on different Yb alloys The model yields an inverse proportionality between the susceptibility atT=0 and the temperatureTM of the susceptibility maximum as functions of the disorder

3 citations

Journal ArticleDOI
TL;DR: In this paper, the impact of a random distribution of non-magnetic impurities on the electron states formed at the surface of a topological insulator is theoretically addressed by a separable pseudo-potential method that allows us to obtain closed expressions for the density of states.
Abstract: We theoretically address the impact of a random distribution of non-magnetic impurities on the electron states formed at the surface of a topological insulator. The interaction of electrons with the impurities is accounted for by a separable pseudo-potential method that allows us to obtain closed expressions for the density of states. Spectral properties of surface states are assessed by means of the Green’s function averaged over disorder realisations. For comparison purposes, the configurationally averaged Green’s function is calculated by means of two different self-consistent methods, namely the self-consistent Born approximation (SCBA) and the coherent potential approximation (CPA). The latter is often regarded as the best single-site theory for the study of the spectral properties of disordered systems. However, although a large number of works employ the SCBA for the analysis of many-impurity scattering on the surface of a topological insulator, CPA studies of the same problem are scarce in the literature. In this work, we find that the SCBA overestimates the impact of the random distribution of impurities on the spectral properties of surface states compared to the CPA predictions. The difference is more pronounced when increasing the magnitude of the disorder.

3 citations

Journal ArticleDOI
TL;DR: In this article, the effects of non-local disorder correlations (alloy short-range order) on the electronic structure of random alloy systems were investigated by mapping the original Anderson disorder problem to that of a selfconsistently embedded cluster.
Abstract: We extend the single-site coherent potential approximation (CPA) to include the effects of non-local disorder correlations (alloy short-range order) on the electronic structure of random alloy systems. This is achieved by mapping the original Anderson disorder problem to that of a selfconsistently embedded cluster. This cluster problem is then solved using the equations of motion technique. The CPA is recovered for cluster size $N_{c}=1$, and the disorder averaged density-of-states (DOS) is always positive definite. Various new features, compared to those observed in CPA, and related to repeated scattering on pairs of sites, reflecting the effect of SRO are clearly visible in the DOS. It is explicitly shown that the cluster-CPA method always yields positive-definite DOS. Anderson localization effects have been investigated within this approach. In general, we find that Anderson localization sets in before band splitting occurs, and that increasing partial order drives a continuous transition from an Anderson insulator to an incoherent metal.

3 citations

Journal ArticleDOI
Th. Eifrig1
TL;DR: In this article, the one-dimensional disordered Hubbard model is investigated in alloy analogy and coherent potential approximation and the temperature dependence of the static susceptibility and the dc conductivity is calculated.
Abstract: The one-dimensional disordered Hubbard model is investigated in alloy analogy and coherent potential approximation. The temperature dependence of the static susceptibility and the dc conductivity is calculated. The numerical investigation shows that especially at low temperatures the results are strongly influenced by disorder. The application of this approximation to the substance NMP-TCNQ is discussed. Es wird das eindimensionale ungeordnete Hubbard-Mokell in Legierungsanalogie und Coherent-Potential-Approximation untersucht. Es werden die Temperaturabhangigkeiten der statischen Suszeptiblitat und der Gleichstromleitfahigkeit berechnet. Die numerische Auswertung zeigt, das insbesondere bei tiefen Temperaturen die Berucksichtigung von Unordnung die Ergebnisse strak beeinflust. Die Anwendung der Ergebnisse dieser Naherung auf die Substanz NMP-TCNQ wird diskutiert.

3 citations

Journal ArticleDOI
TL;DR: In this paper, a new method for calculating the electromagnetic properties of melting snowflakes is presented, which takes account of the topological changes that accompany the melting process, and is based on the coherent potential approximation which is used in modelling composite materials.
Abstract: A new method for calculating the electromagnetic properties of melting snowflakes is presented. This takes account of the topological changes that accompany the melting process, and is based on the coherent potential approximation which is used in modelling composite materials. Sample results for the effective permittivity in partially melted flakes are contrasted with those from previous approaches, as are sample extinction and absorption cross-sections.

3 citations


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