First-principles description of phonons in Ni50Pt50 disordered alloys: The role of relaxation

Subhradip Ghosh, J. B. Neaton, Armin H. Antons, Morrel H. Cohen, P. L. Leath

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Abstract

Using a combination of density-functional perturbation theory and the itinerant coherent potential approximation, we study the effects of atomic relaxation on the inelastic incoherent neutron scattering cross sections of disordered Ni50Pt50 alloys. We build on previous work, where empirical force constants were adjusted ad hoc to agree with experiment. After first relaxing all structural parameters within the local-density approximation for ordered NiPt compounds, density-functional perturbation theory is then used to compute phonon spectra, densities of states, and force constants. The resulting nearest-neighbor force constants are first compared to those of other ordered structures of different stoichiometry and then used to generate the inelastic scattering cross sections within the itinerant coherent potential approximation. We find that structural relaxation substantially affects the computed force constants and resulting inelastic cross sections, and that the effect is much more pronounced in random alloys than in ordered alloys.

Original languageEnglish (US)
Article number024206
Pages (from-to)024206-1-024206-6
JournalPhysical Review B - Condensed Matter and Materials Physics
Volume70
Issue number2
DOIs
StatePublished - Jul 1 2004
Externally publishedYes

All Science Journal Classification (ASJC) codes

  • Electronic, Optical and Magnetic Materials
  • Condensed Matter Physics

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