Dresden 2009 – wissenschaftliches Programm

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O: Fachverband Oberflächenphysik

O 25: Surfaces and films: forces, structure and manipulation

O 25.2: Vortrag

Dienstag, 24. März 2009, 15:15–15:30, SCH A118

Energetics, electronic structure, and packing density of the Ir, Pt, and Au(100) surface reconstructions by all-electron DFT — •Paula Havu1, Ville Havu1, Patrick Rinke1,2, Volker Blum1, and Matthias Scheffler1,21Fritz-Haber-Institut der Max-Planck-Gesellschaft, D-14195 Berlin, Germany — 2University of California at Santa Barbara, CA 93106, USA

Among fcc metals, only the late-5d transition metals Ir, Pt, and Au rearrange by quasihexagonal reconstructions on the nominally quadratic (100) surface structure. However, Ir reconstructs in one direction only [(5×1)], while Au(100) and Pt(100) rearrange in both lateral directions with large unit cells, often characterized as (5× N) (N≥20 in the experimental literature). Elucidating the exact packing density and energetics have been the focus of many experiments, but theory has so far been relegated to either (5×1) approximants, or simplified empirical potentials. Using N = 1, 10, 15, 20, 25, 30 supercell models (up to 786 atoms/cell) and the FHI-aims code [1], we here show how all-electron density-functional theory (DFT) captures the energetics, electronic structure, and lateral packing densities of all three surfaces for different local-density and generalized gradient approximations. Remarkably, the effect of the 2D reconstruction [(5× N) instead of (5×1)] on the surface energy is nearly an order of magnitude bigger for Au than for Pt. DFT captures quantitatively the energetically rather subtle difference in packing densities, which is slightly higher for Au than Pt, consistent with experiment [2]. [1] V. Blum et al., Comp. Phys. Comm., accepted (2008). [2] V. Jahns et al, Surf. Sci. 430, 55 (1999).

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