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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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Journal ArticleDOI
TL;DR: Le formalisme utilise permet de calculer la fonction de Green dans la representation mixte pour un superreseau ayant un general de monocouches.
Abstract: Le formalisme utilise permet de calculer la fonction de Green dans la representation mixte pour un superreseau ayant un general de monocouches. Les couches desordonnees sont decrites dans l'approximation du potentiel coherent. Deux sortes d'arrangement sont etudies. Les resultats montrent la sensibilite du spectre de phonons vis-a-vis de la coherence a longue distance de la composition chimique des superreseaux et de la perfection de leur preparation

5 citations

Journal ArticleDOI
TL;DR: In this paper, the authors investigated conductance fluctuation and shot noise in disordered graphene systems with two kinds of disorder, Anderson type impurities and random dopants, and developed an expansion method based on the coherent potential approximation (CPA) to calculate the average of four Green's functions, and the results are obtained by truncating the expansion up to 6th order in terms of single-site-T-matrix.
Abstract: We report the investigation of conductance fluctuation and shot noise in disordered graphene systems with two kinds of disorder, Anderson type impurities and random dopants. To avoid the traditional exact but time-consuming approach, known as brute-force calculation, which is somehow impractical at low doping concentration, we develop an expansion method based on the coherent potential approximation (CPA) to calculate the average of four Green's functions, and the results are obtained by truncating the expansion up to 6th order in terms of “single-site-T-matrix.” Since our expansion is with respect to “single-site-T-matrix” instead of disorder strength W, good result can be obtained at 6th order for finite W. We benchmark our results against brute-force method on disordered graphene systems as well as the two dimensional square lattice model systems for both Anderson disorder and the random doping. The results show that in the regime where the disorder strength W is small or the doping concentration is low, our results agree well with the results obtained from the brute-force method. Specifically, for the graphene system with Anderson impurities, our results for conductance fluctuation show good agreement for W up to 0.4t, where t is the hopping energy. While for average shot noise, the results are good for W up to 0.2t. When the graphene system is doped with low concentration 1%, the conductance fluctuation and shot noise agrees with brute-force results for large W which is comparable to the hopping energy t. At large doping concentration 10%, good agreement can be reached for conductance fluctuation and shot noise for W up to 0.4t. We have also tested our formalism on square lattice with similar results. Our formalism can be easily combined with linear muffin-tin orbital first-principles transport calculations for light doping nano-scaled systems, making prediction on variability of nano-devices.

5 citations

Journal ArticleDOI
TL;DR: In this article, the coherent potential approximation (CPA) is applied to the description of intermediate valence induced by alloying as observed in the solid solutions Sm1−xRxS where R denotes a rare earth element which is trivalent in the monosulfide.
Abstract: The coherent potential approximation (CPA) is applied to the description of intermediate valence induced by alloying as observed in the solid solutions Sm1−xRxS where R denotes a rare‐earth element which is trivalent in the monosulfide. The description is based on the Falicov‐Kimball model for metal‐insulator transitions generalized to take into account the disorder associated with the R substitution. This disorder is treated within the CPA while the intra‐atomic correlation on the Sm sites is also treated by the CPA in analogy with an alloy of divalent and trivalent Sm ions. The transition to an intermediate valence for Sm as a function of alloy composition is discussed in terms of the results of this treatment.

5 citations

Journal ArticleDOI
TL;DR: In this paper, the electronic structure of superconducting Fe1.03Te0.94S0.06 has been studied by angle resolved photoemission spectroscopy (ARPES).
Abstract: The electronic structure of superconducting Fe1.03Te0.94S0.06 has been studied by angle resolved photoemission spectroscopy (ARPES). Experimental band topography is compared to the calculations using the methods of Korringa-Kohn-Rostoker (KKR) with coherent potential approximation (CPA) and linearized augmented plane wave with local orbitals (LAPW+LO). The region of the Gamma point exhibits two hole pockets and a quasiparticle peak close to the chemical potential with undetectable dispersion. This flat band with mainly dz2 orbital character is formed most likely by the top of the outer hole pocket or is an evidence of the third hole band. It may cover up to 3 % of the Brillouin zone volume and should give rise to a Van Hove singularity. Studies performed for various photon energies indicate that at least one of the hole pockets has a two-dimensional character. The apparently nondispersing peak at the chemical potential is clearly visible for 40 eV and higher photon energies, due to an effect of photoionisation cross section rather than band dimensionality. Orbital characters calculated by LAPW+LO for stoichiometric FeTe do not reveal the flat dz2 band but are in agreement with the experiment for the other dispersions around Gamma in Fe1.03Te0.94S0.06.

5 citations

Journal ArticleDOI
TL;DR: In this paper, the 2p-core level x-ray photoemission spectra in ferromagnetic transition metals, Fe, Co, and Ni using a recently developed ab initio method was studied.
Abstract: We study the 2p-core level x-ray photoemission spectra in ferromagnetic transition metals, Fe, Co, and Ni using a recently developed ab initio method.The excited final states are set up by distributing electrons on the one-electron states calculated under the fully screened potential in the presence of the core hole. We evaluate the overlap between these excited states and the ground state by using one-electron wave functions, and obtain the spectral curves as a function of binding energy. The calculated spectra reproduce well the observed spectra displaying interesting dependence on the element and on the spin of the removed core electron. The origin of the spectral shapes is elucidated in terms of the one-electron states screening the core hole. The magnetic splitting of the threshold energy is also estimated by using the coherent potential approximation within the fully screened potential approximation. It decreases more rapidly than the local spin moment with moving from Fe to Ni. It is estimated to be almost zero for Ni despite the definite local moment about 0.6\mu_B, in agreement with the experiment.

5 citations


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