Fast LMTO-CPA method for electronic structure calculations of disordered alloys: application to Cu-Ni and Cu-Au systems

Abrikosov, I. A.; Vekilov, Yu.H.; Ruban, Andrei V.

doi:10.1016/0375-9601(91)90042-7

Cited by 41 publications

(24 citation statements)

References 15 publications

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“…We have introduced the class of the GCPA theories that are characterized by ͑i͒ a specific ansatz for the kinetic part of the density functional, which is common to all CPA-based theories, and ͑ii͒ an external model that determines the way in which the atomic effective potentials should be reconstructed and the statistical weights to be assigned each. The GCPA class of approximations includes most existing CPA-based density functional theories, to mention a few, the CPA prototype, i.e., the isomorphous CPA, 22,32 SIM-CPA, 44,45 the PCPA, 43 the CPA+ LF, 25 and the nonlocal CPA. 50 The ansatz ͑i͒ consists in applying averaged boundary conditions at the surfaces of each scattering volume and naturally leads to algorithms requiring a number of operation that scales as N. As discussed by Abrikosov and Johansson, 40 CPA-based approximations allow for a careful picture of the spectral properties of metallic alloys.…”

Section: Discussionmentioning

confidence: 99%

“…This failure has stimulated many authors that envisaged CPA generalizations aimed to include the effects of different chemical environments. [42][43][44][45][46] In this paper, we define a class of approximations for DFT-based electronic theories in which most of the above CPA generalizations can be included. We shall refer to the approximations belonging to such a class as GCPA.…”

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: Discussionmentioning

confidence: 99%

Section: A Generalized Coherent-potential Approximations For the Scamentioning

confidence: 99%

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

et al. 2008

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“…It was also shown that the peaks are associated with Au atoms completely surrounded by Cu neighbors. 78,44 As such a configuration must be present in a real random alloy, the traces of the peaks could survive, and the too smooth DOS calculated by the CPA for the Au part of the spectrum has been viewed as a failure of this approximation. 44 In Fig.…”

Section: A Density Of States For a Completely Random Alloymentioning

confidence: 98%

Applicability of the coherent-potential approximation in the theory of random alloys

Abrikosov

Johansson

1998

Phys. Rev. B

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The applicability of the coherent-potential approximation ͑CPA͒ for the description of electronic properties of completely random alloys is investigated. This is done by calculating the density of states and the total energy for different systems and by comparing the results with those obtained for large supercells consisting of up to 320 atoms in the framework of the order-N locally self-consistent Green's function method. Thereby it is found that in the framework of the CPA one obtains a reliable description of the electronic structure of random alloys. The total energy of a completely disordered alloy can also be reliably estimated provided an appropriate account is given for the electrostatic contribution to the one-electron potential and energy. Therefore, we conclude that the CPA can be safely applied to study the influence of disorder on various properties of metallic alloys for which the muffin-tin or atomic sphere approximation is sufficient and the chemical contribution to the total energy dominates. ͓S0163-1829͑98͒03122-1͔

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“…This results from the implicit assumption of an isomorphous model which furthermore implies that the Madelung contribution to the energy averages to zero. This aspect of KKR-CPA has been much discussed, [21][22][23][24][25] and a number of schemes have been developed for including additional Coulomb correlations. 24,25 Here we will use the LDA-KKR-CPA in its original form and will use the LSMS method to directly study fluctuations in magnetic moments that result from local environment effects.…”

Section: ͑7͒mentioning

confidence: 99%

Magnetic structure ofNi-richNi1−xTax
Moghadam
¹
,
Stocks
²

2005
Phys. Rev. B
12
1
6
0
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Tantalum is used in magnetic devices as a buffer layer. However, Ta has deleterious effects on the magnetic properties. We study the magnetic structure of Ni-rich Ni 1−x Ta x alloys using the Korrianga-Kohn-Rostoker Coherent-potential approximation ͑KKR-CPA͒ method. We show that the average magnetic moment vanishes at ϳ12%Ta. The magnetism is shown to be Stoner-like. We also study the magnetic structure of Ta impurities embedded in pure Ni using supercell models. We find that the impurity atom suppresses the moment on neighboring Ni atoms. Finally, we study the effects of Ta additions on moment formation in permalloy ͑Ni 0.8 Fe 0.2 solid solutions͒ using the KKR-CPA method. It is shown that the average moment vanishes at ϳ45% Ta. The effects of Ta on the local moments are also investigated. These calculations are performed using the order-N locally self-consistent multiple-scattering method.

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Fast LMTO-CPA method for electronic structure calculations of disordered alloys: application to Cu-Ni and Cu-Au systems

Cited by 41 publications

References 15 publications

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

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

Applicability of the coherent-potential approximation in the theory of random alloys

Magnetic structure ofNi-richNi1−xTax
Moghadam
¹
,
Stocks
²

2005
Phys. Rev. B
12
1
6
0
View full text Add to dashboard Cite

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Fast LMTO-CPA method for electronic structure calculations of disordered alloys: application to Cu-Ni and Cu-Au systems

Cited by 41 publications

References 15 publications

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

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

Applicability of the coherent-potential approximation in the theory of random alloys

Magnetic structure ofNi-richNi1−xTaxMoghadam1, Stocks2 2005Phys. Rev. B12160View full textAdd to dashboardCite

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Magnetic structure ofNi-richNi1−xTax
Moghadam
¹
,
Stocks
²

2005
Phys. Rev. B
12
1
6
0
View full text Add to dashboard Cite