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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, a statistical mechanical method (CVM) was developed for calculating superstructure phase equilibria derived from say, the fcc parent lattice, which can be used to obtain phase diagrams, such as effective pair interaction ratios.
Abstract: Many stable or metastable intermetallic phases useful to the alloy designer have crystal structures which are ordered superstructures of a parent disordered phase. A highly reliable statistical mechanical method (CVM) has now been developed for calculating such superstructure phase equilibria derived from say, the fcc parent lattice. To obtain phase diagrams, one needs certain physical parameters, such as effective pair interaction ratios. It is possible, in principle, to extract these parameters from band structure calculations in the coherent potential approximation (CPA), particularly from recently developed cluster-CPA techniques. If sufficient accuracy can be achieved, truly first-principles phase diagram calculations may soon become feasible.
2 citations
TL;DR: In this article, the authors used the Green function method and the chemisorption theory of Einstein and Schrieffer to calculate the energy of O and CO on the multilayer segregated Ni-Cu disordered binary alloy within the many-coupled coherent potential approximation.
Abstract: The Green function method and the chemisorption theory of Einstein and Schrieffer are used to calculate the chemisorption energies of O and CO on the multilayer segregated Ni-Cu disordered binary alloy within the many-coupled self-consistent coherent potential approximation. In general cases, the chemisorption-induced surface segregation can change the surface component and the chemisorption property to varying degrees. When the mutual influence of chemisorption and multilayer segregation is considered, the changes appear slightly mild. The chemisorption energy for O/Ni-Cu (CO/Ni-Cu) depends sensitively on O(CO) coverage θ, and decreases with increasing θ.
2 citations
TL;DR: In this paper, a theory for studying the local electronic structure at the surfaces of a disordered binary alloy in the presence of short-range order (SRO) in the system, the alloy being considered as having Bethe lattice topology.
Abstract: The authors present here a theory for studying the local electronic structure at the surfaces of a disordered binary alloy in the presence of short-range order (SRO) in the system, the alloy being considered as having Bethe lattice topology. This theory offers a way of going beyond the single-site coherent potential approximation (CPA) by allowing the incorporation of the effects of environmental fluctuations. This method leads to an effective medium for this semiinfinite system which can be obtained in a very elegant way by modifying the CPA effective medium. The well-known limits of complete segregation and binary sequence are exactly obtained and, in the random case, the CPA results for the surfaces are reproduced.
2 citations
TL;DR: In this paper, the first mean-field approximation, the coherent potential approximation, does not treat Coulomb effects correctly and has been improved by changing the way the mean field approximation is implemented.
Abstract: Mean-field approximations are used to find approximate solutions to the one-electron equations for the electronic states in disordered alloys because ordinary band-theory approaches are not applicable. The first mean-field approximation, the coherent potential approximation, does not treat Coulomb effects correctly. This has been improved by changing the way the mean-field approximation is implemented. It may be that this experience with mean-field approximations will be useful to the combination of many-body theory and mean-field theory that has produced the dynamical coherent potential approximation and dynamical mean field theory for treating strongly correlated electron systems.
2 citations
TL;DR: In this paper, the authors extended the approach by Usami and Moriya on the ferromagnetic metals which makes use of the single site coherent potential approximation to the antiferromagnetic cases.
Abstract: Antiferromagnetic metals at finite temperature are discussed based on a unified spin fluctuation theory of Moriya and Takahashi. We extend the approach by Usami and Moriya on the ferromagnetic metals which makes use of the single site coherent potential approximation to the antiferromagnetic cases. Based on a simple model of antiferromagnetism, results of numerical calculations for the 3d-metals with a FCC and a BCC structure are presented.
2 citations