Charge-correlation effects in calculations of atomic short-range order in metallic alloys
- Department of Physics, University of Cincinnati, Cincinnati, Ohio 45221 (United States)
- Department of Physics, University of Warwick, Coventry CV4 7AL (United Kingdom)
- Department of Materials Science and Engineering, University of Illinois, Urbana, Illinois 61801 (United States)
The {open_quotes}local{close_quotes} chemical environment that surrounds an atom directly influences its electronic charge density. These atomic charge correlations play an important role in describing the Coulomb and total energies for random substitutional alloys. Although the electronic structure may be well represented by a single-site theory, such as the coherent potential approximation, the electrostatic energy is not as well represented when these charge correlations are ignored. For metals, including the average effect from the charge correlation coming from only the nearest-neighbor shell has been shown to be sufficient to determine accurately the energy of formation. In this paper, we incorporate such charge correlations into the concentration-wave approach for calculating the atomic short-range order in random (substitutional) alloys. We present changes within the formalism, and apply the resulting equations to equiatomic nickel platinum. By including these effects, we obtain significantly better agreement with experimental data. In fact, particular to NiPt, a consequence of the charge correlation is a screening which cancels much of the electrostatic contribution to the energy and thus to the atomic short-range order, resulting in agreement with a picture originally outlined using only {open_quotes}band-energy{close_quotes} contributions. {copyright} {ital 1998} {ital The American Physical Society}
- OSTI ID:
- 636173
- Journal Information:
- Physical Review, B: Condensed Matter, Vol. 57, Issue 24; Other Information: PBD: Jun 1998
- Country of Publication:
- United States
- Language:
- English
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