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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 energy bands of the ternary alloys GaxIn1-xP, GaAs1-XPx, GaxAs 1-xAs and InAs1xPx were calculated in the coherent-potential approximation (CPA) using the tight-binding Hamiltonian.
Abstract: Electronic band structures of the ternary alloys GaxIn1-xP, GaAs1-xPx, GaxIn1-xAs and InAs1-xPx are calculated in the coherent-potential approximation (CPA) using the tight-binding Hamiltonian. The CPA energy bands are reported for the first time for the GaxIn1-xAs and InAs1-xPx systems. The calculated variation of important direct and indirect energy gaps with composition x and their bowing is compared with the available experimental data, and good agreement is found for all the four ternary alloys studied.
7 citations
TL;DR: This work provides the theoretical foundation of a real-space cluster CPA that is causal, enforces the proper symmetries of the effective medium, and includes effects of multiple scattering of the same and nearby defects, which is essential for strong defects.
Abstract: We present an investigation of disordered photonic crystals (PhCs) based on the combination of photonic Wannier functions with the concept of the coherent potential approximation (CPA). In particular, we provide the theoretical foundation of a real-space cluster CPA that is causal, enforces the proper symmetries of the effective medium, and includes effects of multiple scattering of the same and nearby defects, which is essential for strong defects. Based on this, we present results for the density of states of disordered PhCs for different types of disorder. Our results are thus relevant to such diverse areas as random lasing and the analysis of fabricational imperfections in PhCs.
7 citations
TL;DR: In this article, a model for the band-gap energy of InxGayAl1−x−yN is developed based on modification of the simplified coherent potential approximation, and the parameters of the model are obtained by fitting the experimental bandgap energies of their ternary alloys.
Abstract: Based on modification of the simplified coherent potential approximation, a model for the band-gap energy of InxGayAl1−x−yN is developed. The parameters of the model are obtained by fitting the experimental band-gap energy of their ternary alloys. It is found that the results agree with the experimental values better than those reported by others, and that the band-gap reduction of InxGayAl1−x−yN with increasing In or Ga content is mainly due to enhanced intraband coupling within the conduction band, and separately within the valence band.
7 citations
TL;DR: In this paper, it was shown that the dynamical coherent potential approximation (CPA) theory combined with the harmonic approximation (HA) is applicable to the quantitative description of magnetic properties in high dimensional systems, but one needs to take into account higher-order dynamical corrections in orde...
Abstract: Magnetic and electronic properties of the Hubbard model on the Bethe and fcc lattices in infinite dimensions have been investigated numerically on the basis of the dynamical coherent potential approximation (CPA) theory combined with the harmonic approximation (HA) in order to clarify the quantitative aspects of the theory. It is shown that the dynamical CPA+HA reproduces well the sublattice magnetizations, the magnetizations, susceptibilities, and the Neel temperatures ( T N ) as well as the Curie temperatures calculated by the Quantum Monte-Carlo (QMC) method. The critical Coulomb interactions ( U c ) for the metal–insulator (MI) transition are also shown to agree with the QMC results above T N . Below T N , U c deviate from the QMC values by about 30% at low temperature regime. These results indicate that the dynamical CPA+HA is applicable to the quantitative description of the magnetic properties in high dimensional systems, but one needs to take into account higher-order dynamical corrections in orde...
7 citations
TL;DR: In this article, the effects of magnetic short-range order and non-local correlations on magnetism were discussed from a local point of view on the basis of the dynamical coherent potential approximation (CPA) which completely takes account of dynamical spin and charge fluctuations within the single-site approximation.
Abstract: Electron correlation effects on magnetism are discussed from a local point of view on the basis of the dynamical coherent potential approximation (CPA) which completely takes account of the dynamical spin and charge fluctuations within the single-site approximation. The dynamical CPA is equivalent to other single-site theories of strongly correlated electrons: the many-body CPA, the dynamical mean-field theory, and the projection operator method CPA. The method is shown to describe both the dynamical effects on magnetic properties and the many-body band structure on the same footing. The effects of orbital degeneracy and the realistic calculation scheme are discussed with emphasis on Hund's rule coupling. Two types of theories for non-local correlations, the molecular dynamics approach and the self-consistent projection operator approach, are presented. The effects of magnetic short-range order and non-local correlations are discussed with some numerical results.
7 citations