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Optimal site-centered electronic structure basis set from a displaced-center expansion: Improved results via a priori estimates of saddle points in the density
Physical Review B (2009)
  • Aftab Alam, University of Illinois at Urbana-Champaign
  • Duane D. Johnson, University of Illinois at Urbana-Champaign
Abstract
Site-centered, electronic-structure methods use an expansion inside nonoverlapping “muffin-tin” (MT) spheres plus an interstitial basis set. As the boundary separating the more spherical from nonspherical density between atoms, the “saddle-point” radii (SPR) in the density provide an optimal spherical region for expanding in spherical harmonics, as used in augmented plane wave, muffin-tin orbital, and multiple-scattering [Korringa, Kohn, and Rostoker (KKR)] methods. These MT-SPR guarantee unique, convex Voronoi polyhedra at each site, in distinction to Bader topological cells. We present a numerically fast, two-center expansion to find SPR a priori from overlapping atomic charge densities, valid also for disordered alloys. We adopt this MT-SPR basis for KKR in the atomic sphere approximation and study (dis)ordered alloys with large differences in atomic size (fcc CoPt and bcc CrW). For this simple and unique improvement, we find formation energies and structural parameters in strikingly better agreement with more exact methods or experiment, and resolve issues with former results.
Publication Date
September 15, 2009
Publisher Statement
Copyright 2009 American Physical Society
Citation Information
Aftab Alam and Duane D. Johnson. "Optimal site-centered electronic structure basis set from a displaced-center expansion: Improved results via a priori estimates of saddle points in the density" Physical Review B Vol. 80 Iss. 12 (2009)
Available at: http://works.bepress.com/duane_johnson/40/