Topic
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 presented a calculation of Seebeck coefficient derived by Kubo-Greenwood formula with the density functional theory for transition metals and metal alloys, showing that the role of mean free time associated to each orbital is quite important to obtain an accurate result of the Seebeck coefficients.
Abstract: We present a calculation of Seebeck coefficient derived by Kubo–Greenwood formula with the density functional theory. The electronic structure calculation being the Korringa–Kohn–Rsestoker Green's function method with coherent potential approximation and local density functional method (KKR-CPA-LDA). We show the results for transition metals and metal alloys. In particular, the result for palladium-silver alloy shows good agreement with the experimental data. This calculation shows that the role of mean free time associated to each orbital is quite important to obtain an accurate result of the Seebeck coefficient.
6 citations
TL;DR: In this article, a generalization of the original single-site coherent potential approximation (CPA) applicable to compositionally modulated alloys is proposed and shown to be more accurate than the original CPA from which it was obtained.
6 citations
TL;DR: In this article, the role of excited impurity orbitals in doped semiconductors is discussed and it is shown that they are crucial elements for the case of n-doped Si or Ge at intermediate concentrations near the metal-non-metal transition.
Abstract: The role of the excited impurity orbitals in doped semiconductors is discussed. It is shown that they are crucial elements for the case of n-doped Si or Ge at intermediate concentrations near the metal-non-metal transition. This is due to the fact that, for this range of concentrations, the states with energies near the Fermi level have mainly an 'excited' character. The system is described by a tight-binding Hamiltonian with a basis composed by two orbital per site. Only the local electron repulsion is considered. The correlation is treated in the coherent potential approximation. To calculate the configurational averages a diagrammatic scheme is developed. It represents an extension of the Matsubara and Toyozawa method for the case of two hybridised bands in the presence of electronic correlation.
6 citations
TL;DR: In this paper, the two-particle Green function in the Hubbard model using the recently developed?-CPA, a hybrid treatment that applies the coherent potential approximation?(CPA) up to a time related to the inverse of the bandwidth, after which the system is averaged using the virtual crystal approximation.
Abstract: We treat the two-particle Green function in the Hubbard model using the recently developed ?-CPA, a hybrid treatment that applies the coherent potential approximation?(CPA) up to a time ? related to the inverse of the bandwidth, after which the system is averaged using the virtual crystal approximation. This model, with suitable approximations, does predict magnetism for a modified Stoner criterion. The evaluation of the two-particle propagator in the ?-CPA requires the solution of the pure CPA, within whose formalism the vertex correction and the weighted Green functions are obtained. The dynamical susceptibility, including the vertex correction and the weighted scattering by the residual interaction, is calculated and shows a spin wave spectrum in the ferromagnetic regime.
6 citations
TL;DR: In this article, a quasiparticle modification of the generalized Kadanoff-Baym ansatz is motivated formally and verified on numerical data, and the results are used to test the semigroup property of the propagators and the analogous factorization of the particle correlation function known as the generalized kadanoff -Baym.
Abstract: For a model two-band semiconductor with static disorder, suddenly illuminated by intense light, the averaged non-equilibrium Green function can be obtained within the coherent potential approximation. Explicit solutions found previously are analyzed on numerical examples of the transient photoexcited distribution. The results are used to test the semigroup property of the propagators and the analogous factorization of the particle correlation function known as the generalized Kadanoff-Baym ansatz. Both properties hold much better if quasiparticle states are used instead of the bare particles. The quasiparticle modification of the ansatz is motivated formally and verified on numerical data
6 citations