Regensburg 2010 – scientific programme
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O: Fachverband Oberflächenphysik
O 84: Density functional theory and beyond for real materials IV
O 84.4: Talk
Friday, March 26, 2010, 12:00–12:15, H34
Surface Energies of Transition Metals with Density-Functional Theory and beyond — Aloysius Soon1, Bo Li2, Martin Fuchs1, and •Matthias Scheffler1 — 1Fritz-Haber-Institut der MPG, Berlin, Germany — 2University of California Santa Barbara, California, USA
Determining surface energies of metals is, to date, a great challenge, both theoretically and (even more so) experimentally. Density-functional theory (DFT) calculations of metal surface energies within the local-density approximation have provided understanding of qualitative trends. Yet absolute surface energies, in particular of d-metals, exhibit significant uncertainties related to the description of exchange-correlation (XC). A more sophisticated treatment of XC for real metals, beyond present-day gradient-corrected approximations is however still an open challenge. In particular, this requires a careful (re-)analysis of the bonding between metal atoms in the bulk and at the surface in terms of explicitly correlated approaches. Such an analysis is attempted in this paper.
Employing the cluster correction scheme1, we derive surface energies beyond the (semi-)local DFT, using hybrid-DFT XC functionals as well as higher-level approaches (e.g. exact exchange plus the RPA for correlation – EX+cRPA). We find the surface energies of pristine metals to be poorly described (i.e. largely underestimated by about 30 %) by hybrid-DFT XC functionals, while the EX+cRPA provides a promising approach towards describing surface energetics. [1] Q.-M. Hu et al., Phys. Rev. Lett. 98, 176103 (2007); 99, 169903(E).