Coulomb energies in alloys

Faulkner, John; Wang, Yang; Stocks, G. M.

doi:10.1103/physrevb.55.7492

Cited by 40 publications

(90 citation statements)

References 42 publications

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“…The next step will be to combine it with DFT, 27 which will also enable charge correlations 32,33,34 and local lattice displacements 40 to be systematically taken into account for alloys. Then, the SRO parameter α will need to be coarse-grained via Eqs.…”

Section: Discussionmentioning

confidence: 99%

Effects of short-range order on the electronic structure of disordered metallic systems

et al. 2005

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For many years the Korringa-Kohn-Rostoker coherent-potential approximation (KKR-CPA) has been widely used to describe the electronic structure of disordered systems based upon a firstprinciples description of the crystal potential. However, as a single-site theory the KKR-CPA is unable to account for important environmental effects such as short-range order (SRO) in alloys and spin fluctuations in magnets, amongst others. Using the recently devised KKR-NLCPA (where NL stands for nonlocal), we show how to remedy this by presenting explicit calculations for the effects of SRO on the electronic structure of the bcc Cu50Zn50 solid solution.

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Section: Discussionmentioning

confidence: 99%

Effects of short-range order on the electronic structure of disordered metallic systems

et al. 2005

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“…It was not until the 1990s that developments in computer hardware and so-called order-N methods, such as the locally self-consistent multiple-scattering (LSMS) 10 and the locally self-consistent Green's function (LSGF) 11,12 methods, allowed the distribution of site properties within disordered alloys to be determined in an ab initio fashion. These calculations revealed a surprisingly simple relationship between the net charge on a site and its Madelung potential -the Q-V relations 13,14 :…”

Section: Introductionmentioning

confidence: 99%

“…The MLCM has been shown to reproduce the values of Q i and V i obtained from order-N calculations to a high degree of accuracy -when the model is appropriately parameterized 21 . However, the MLCM has been criticized for the fact that it has too many free parameters 14,23 . In an attempt to reduce the number of free parameters in the MLCM, it was proposed in Ref.…”

Section: Introductionmentioning

confidence: 99%

Lattice charge models and core level shifts in disordered alloys

Underwood

Cole²

2013

J. Phys.: Condens. Matter

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Differences in core level binding energies between atoms belonging to the same chemical species can be related to differences in their intra-and extra-atomic charge distributions, and differences in how their core holes are screened. With this in mind, we consider the charge-excess functional model (CEFM) for net atomic charges in alloys [E. Bruno et al., Phys. Rev. Lett. 91, 166401 (2003)]. We begin by deriving the CEFM energy function in order to elucidate the approximations which underpin this model. We thereafter consider the particular case of the CEFM in which the strength of the 'local interactions' within all atoms are the same. We show that for binary alloys the ground state charges of this model can be expressed in terms of charge transfer between all pairs of unlike atoms analogously to the linear charge model [R. Magri et al., Phys. Rev. B 42, 11388 (1990)]. Hence the model considered is a generalization of the linear charge model for alloys containing more than two chemical species. We then determine the model's unknown 'geometric factors' over a wide range of parameter space. These quantities are linked to the nature of charge screening in the model, and we illustrate that the screening becomes increasingly universal as the strength of the local interactions is increased. We then use the model to derive analytical expressions for various physical quantities, including the Madelung energy and the disorder broadening in the core level binding energies. These expressions are applied to ternary random alloys, for which it is shown that the Madelung energy and magnitude of disorder broadening are maximized at the composition at which the two species with the largest 'electronegativity difference' are equal, while the remaining species having a vanishing concentration. This result is somewhat counterintuitive with regards to the disorder broadening since it does not correspond to the composition with the highest entropy. Finally, the model is applied to CuPd and CuZn random alloys. The model is used to deduce the effective radii associated with valence electron charge transfer for Cu, Pd and Zn in these systems for use in the ESCA potential model of X-ray photoelectron spectroscopy. The effective radii are found to be R1/3, where R1 is the nearest neighbor distance, with only small variations between chemical elements and between different systems. The model provides a framework for rationalising the disorder broadenings in these systems: they can be understood in terms of an interplay between the broadening in the Madelung potentials and the broadening in the intra-atomic electrostatic potentials.

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“…If all the material specific coefficients, a α and b α , were specified by the mean alloy concentrations, one would have a set of N+1 equations, Eqs. (11) and (4), and N unknown quantities to be determined, the q i . In general, the determinant of this set of equations is not singular and, hence, the problem would be overdetermined.…”

Section: The Charge Excess Functionalmentioning

confidence: 99%

“…Their model simply assumes the charge excesses to be proportional to the number of unlike nearest neighbours. When the development of order N calculation allowed a deeper investigation of the problem [3,4], it was readily clear that such a simple model was not able to describe the details of the Cu for the 1024 atoms bcc Cu0.50Zn0.50 random alloy sample (see Table I). Open circles: LSMS calculations (Ref.…”

Section: Charge Excesses Versus Local Environmentsmentioning

confidence: 99%

Charge Distributions in Metallic Alloys: A Charge Excess Functional Theory Approach

Bruno

Complex Inorganic Solids

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Coulomb energies in alloys

Cited by 40 publications

References 42 publications

Effects of short-range order on the electronic structure of disordered metallic systems

Effects of short-range order on the electronic structure of disordered metallic systems

Lattice charge models and core level shifts in disordered alloys

Charge Distributions in Metallic Alloys: A Charge Excess Functional Theory Approach

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