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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: Using the coherent potential approximation, the zero-temperature Mott transition in the half-filled Hubbard model on the honeycomb lattice was studied in this paper, where a pseudogap is already present for the non-interacting case, the gap will not occur until the onsite Coulomb repulsion exceeds a critical value U ≈ 36t, where t is the hopping integral.
Abstract: Using the coherent potential approximation, we study zero-temperature Mott transition in the half-filled Hubbard model on the honeycomb lattice Although a pseudogap is already present for the non-interacting case, the gap will not occur until the onsite Coulomb repulsion exceeds a critical value U ≈ 36t, where t is the hopping integral When increasing U/t, the density of states at the Fermi energy first goes up gradually from zero and after reaching a maximum it goes down to zero again Our calculated critical interaction UC/t is in very good agreement with the ones obtained by quantum Monte Carlo simulation and cluster dynamical mean-field theory
6 citations
TL;DR: In this article, the authors extended the single-band model Hamiltonian used by Velicky, Kirkpatrick, and Ehrenreich (VKE) in their classic paper on the electronic theory of nondilute binary alloys is extended to the ternary-alloy case, and a number of results are derived.
Abstract: The single-band model Hamiltonian used by Velick\'y, Kirkpatrick, and Ehrenreich (VKE) in their classic paper on the electronic theory of nondilute binary alloys is extended to the ternary-alloy case, and a number of results are derived. It is shown by direct calculation that the coherent-potential approximation (CPA) preserves the first seven moments of the density of states and the spectral density. Diagrammatic considerations put the highest moments at eight and seven, respectively. Exact information concerning the effective Hamiltonian leads via the Kramers-Kronig dispersion relation to a series of sum rules involving the self-energy. The localization theorem predicts the existence of two or three well-separated subbands for which the self-energy may have a pole between adjacent subbands. These singularities are also found in the CPA. Within the appropriate limits, all calculated quantities and various limiting behaviors (virtual crystal, dilute alloy, and the atomic limit), reduce to the binary-alloy results of VKE. A semielliptic reference density of states is used for a numerical presentation of the CPA description of the model ternary alloy. New numerical examples of the $\stackrel{\ensuremath{\rightarrow}}{\mathrm{k}}$-independent properties of the CPA are exhibited for the self-energy, the total density of states, and the partial densities of states, over a wide range of concentrations and scattering-potential strengths. Results are also displayed for the Bloch-wave spectral density. This $\stackrel{\ensuremath{\rightarrow}}{\mathrm{k}}$-dependent quantity provides information concerning the validity of describing the states of the disordered alloy in terms of quasiparticles with wave vector $\stackrel{\ensuremath{\rightarrow}}{\mathrm{k}}$.
6 citations
TL;DR: In this paper, the effects of Zn on the band gap and effective masses of quaternary alloy Hg1−x−yCdxZnyTe were investigated using both the virtual crystal approximation and the coherent potential approximation.
Abstract: The electronic structure of Zn‐containing Hg1−xCdxTe is investigated and the effects of Zn on the band gap and effective masses are estimated. In these studies, ZnTe is treated as an additional alloy constituent and the resulting quaternary alloy Hg1−x−yCdxZnyTe is modeled using both the virtual‐crystal approximation and the coherent potential approximation. Numerical results are obtained by utilizing tight‐binding band structures of the constituent compounds. Results are presented for the variation of the band gap and electron effective mass with Zn composition y for fixed Cd composition x, and for the dependence of the electron and hole effective masses on Zn composition for two different fixed band gaps in the infrared regime. The results show that Zn‐induced alloy disorder effects can be important for determining both the band gap and the effective masses, but that for constant band‐gap material the effective masses are almost independent of y.
6 citations
TL;DR: The density matrix of an Ising model with quenched random interactions is written in terms of a translationally invariant effective Hamiltonian, Heff, with a random perturbation as mentioned in this paper.
Abstract: The density matrix of an Ising model with quenched random interactions is written in terms of a translationally invariant effective Hamiltonian, Heff, with a random perturbation Heff is determined by requiring, as in the coherent potential approximation, that repeated scatterings from a single site do not affect the partition function It is shown that Heff describes an annealed random system
6 citations
TL;DR: In this article, the electronic densities of states in PtMn and PtCr alloys were calculated in the cluster coherent potential approximation, and numerical calculations were made for the concentration near ordering L12 type structure.
Abstract: The electronic densities of states in PtMn and PtCr alloys are calculated in the cluster coherent potential approximation. Numerical calculations are made for the concentration near ordering L12 type structure. Changes in the values and the positions of the peaks in the densities of states are observed.
6 citations