Mean-field approximations for the electronic states in disordered alloys

Faulkner, John; Pella, S.; Rusanu, Aurelian; Puzyrev, Yevgeniy; Leventouri, Th.; Stocks, G. M.; Újfalussy, B.

doi:10.1080/14786430500398417

Cited by 3 publications

(5 citation statements)

References 40 publications

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“…The limitation n/N << 1, that comes from the above argument, does not impose any upper bound on the maximum length scale at which chemical fluctuations can be stud- ied and it is of no practical importance provided that N is large enough to ensure a good approximation τ c a . As reported in the literature 47,49 , it seems that N about 100 is already enough. iv) Although we have suggested that the coherent scattering matrix from random alloys GCPA calculations can be used for ordered alloys too, we are aware of the limitations of such a physical picture.…”

Section: Generalized Coherent Potential Approximations (Gcpa) and Cha...mentioning

confidence: 64%

“…The limitation n / N Ӷ 1 that comes from the above argument does not impose any upper bound on the maximum length scale at which chemical fluctuations can be studied and it is of no practical importance provided that N is large enough to ensure a good approximation គ a c . As reported in the literature, 47,49 it seems that N of about 100 is already enough.…”

Section: ͑30͒mentioning

confidence: 66%

“…Another point we wish to address is concerned with the value of the chemical potential µ in Eq. (47). In a recent paper, Drchal et al 61 argued that µ should be always zero since the Fourier transform of the Madelung coefficients with L = L ′ = (0, 0) diverges as k → ∞ implying that the sum of the charge excesses q i,00 must vanish, automatically satisfying the electroneutrality constraint.…”

Section: A Generalized Version Of the Charge Excess Functional Theorymentioning

confidence: 99%

“…Its external model is the isomorphous assumption ͑identical effective potentials for atoms of the same atomic species and weights proportional to the respective atomic concentrations͒. Another example is the polymorphous CPA ͑PCPA͒ of Ujfalussy et al 43,47,48 The external model is constructed by using an auxiliary supercell containing N atoms, usually hundreds or thousands, each to be weighted with the same weight. The effective site potentials are reconstructed on the same supercell via Eq.…”

Section: A Generalized Coherent-potential Approximations For the Scamentioning

confidence: 99%

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Coarse-grained density functional theories for metallic alloys: Generalized coherent-potential approximations and charge-excess functional theory

et al. 2008

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The class of the generalized coherent-potential approximations ͑GCPAs͒ to the density functional theory ͑DFT͒ is introduced within the multiple scattering theory formalism with the aim of dealing with ordered or disordered metallic alloys. All GCPA theories are based on a common ansatz for the kinetic part of the Hohenberg-Kohn functional and each theory of the class is specified by an external model concerning the potential reconstruction. Most existing DFT implementations of CPA-based theories belong to the GCPA class. The analysis of the formal properties of the density functional defined by GCPA theories shows that it consists of marginally coupled local contributions. Furthermore, it is shown that the GCPA functional does not depend on the details of the charge density and that it can be exactly rewritten as a function of the appropriate charge multipole moments to be associated with each lattice site. A general procedure based on the integration of the qV laws is described that allows for the explicit construction of the same function. The coarse-grained nature of the GCPA density functional implies a great deal of computational advantages and is connected with the O͑N͒ scalability of GCPA algorithms. Moreover, it is shown that a convenient truncated series expansion of the GCPA functional leads to the charge-excess functional ͑CEF͒ theory ͓E. Bruno et al., Phys. Rev. Lett. 91, 166401 ͑2003͔͒, which here is offered in a generalized version that includes multipolar interactions. CEF and the GCPA numerical results are compared with status of art linearized augmented plane wave ͑LAPW͒ fullpotential density functional calculations for 62 bcc-and fcc-based ordered CuZn alloys, in all the range of concentrations. Two facts clearly emerge from these extensive tests. In the first place, the discrepancies between GCPA and CEF results are always within the numerical accuracy of the calculations, both for the site charges and the total energies. In the second place, the GCPA ͑or the CEF͒ is able to very carefully reproduce the LAPW site charges and a good agreement is obtained also about the total energies.

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Section: Generalized Coherent Potential Approximations (Gcpa) and Cha...mentioning

confidence: 64%

Section: ͑30͒mentioning

confidence: 66%

Section: A Generalized Version Of the Charge Excess Functional Theorymentioning

confidence: 99%

Section: A Generalized Coherent-potential Approximations For the Scamentioning

confidence: 99%

See 2 more Smart Citations

Coarse-grained density functional theories for metallic alloys: Generalized coherent-potential approximations and charge-excess functional theory

et al. 2008

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“…An alternative method is the mean-field-type coherent potential approximation (CPA) [13], often implemented within the Korringa-Kohn-Rostoker (KKR) [14][15][16] multiple scattering formalism for enhanced model accuracy [17]. This approach simulates interactions between electrons and the potential via propagators (Green's functions) and approximates the varying potentials of random alloys by introducing an effective medium potential from a perfectly ordered lattice [18].…”

Section: Introductionmentioning

confidence: 99%

Modeling Off-Stoichiometry Materials with a High-Throughput Ab-Initio Approach

Yang

Oses²,

Curtarolo³

2016

Chem. Mater.

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Predicting material properties of disordered systems remains a long-standing and formidable challenge in rational materials design. To address this issue, we introduce an automated software framework capable of modeling partial occupation within disordered materials using a high-throughput (HT) first principles approach. At the heart of the approach is the construction of supercells containing a virtually equivalent stoichiometry to the disordered material. All unique supercell permutations are enumerated and material properties of each are determined via HT electronic structure calculations. In accordance with a canonical ensemble of supercell states, the framework evaluates ensemble average properties of the system as a function of temperature. As proof of concept, we examine the framework's final calculated properties of a zinc chalcogenide (ZnS1−xSex), a wide-gap oxide semiconductor (MgxZn1−xO), and an iron alloy (Fe1−xCux) at various stoichiometries. arXiv:1511.04373v1 [cond-mat.mtrl-sci]

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