Dresden 2009 – wissenschaftliches Programm

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O: Fachverband Oberflächenphysik

O 42: Poster Session II (Nanostructures at surfaces: arrays; Nanostructures at surfaces: Dots, particles, clusters; Nanostructures at surfaces: Other; Nanostructures at surfaces: Wires, tubes; Metal substrates: Adsorption of O and/or H; Metal substrates: Clean surfaces; Metal substrates: Adsorption of organic/bio moledules; Metal substrates: Solid-liquid interfaces; Metal substrates: Adsorption of inorganic molecules; Metal substrates: Epitaxy and growth; Heterogeneous catalysis; Surface chemical reactions; Ab-initio approaches to excitations in condensed matter; Organic, polymeric, biomolecular films– also with adsorbates; Particles and clusters)

O 42.36: Poster

Mittwoch, 25. März 2009, 17:45–20:30, P2

Entropy changes stability of Au(110) surface reconstructions — Eva Rauls, •Marc Landmann, and Wolf Gero Schmidt — Lehrstuhl für Theoretische Physik, Universität Paderborn

In contrast to the unreconstructed single-crystal surfaces of Cu and Ag, the Au(110) surface is subject to short range reconstructions of a missing row type. Even the lowest energy surface in (111) direction shows a long range surface reconstruction. Experimentally, Au(110) reconstructions with (1x2) and (1x3) periodicity are observed [1,2], while in theoretical works, the stability order is discussed controversially [3].

We have carried out density-functional theory calculations to resolve this controversy. If we consider the contributions of vibrational entropy, we find different stabilizations for the different reconstructions. This leads to a temperature dependent stability order, with the (1x3) reconstruction being the most stable structure at zero temperature, while, at room temperature, the most often observed (1x2) reconstruction is most stable, demonstrating the crucial role of entropy.

[1] W. Moritz and D. Wolf, Surf. Sci. 88, L29, (1979)

[2] G. Binning, H. Rohrer, Ch. Gerber and E. Weibel, Surf. Sci. 131, L379, (1983)

[3] A. Y. Lozovoi and A. Alavi, Phys. Rev. B 68, 245416, (2003)