Regensburg 2004 – wissenschaftliches Programm

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O: Oberflächenphysik

O 43: Adsorption an Oberflächen IV

O 43.2: Vortrag

Freitag, 12. März 2004, 11:30–11:45, H36

The on-surface ordering behavior of O/Rh(111) and H/Pd(111) studied from first-principles — •Cesar Lazo1, Frerich Keil1, Karsten Reuter2, and Matthias Scheffler21TU Hamburg-Harburg, Eissendorfer Str. 38, 21071 Hamburg — 2Fritz-Haber-Institut, Faradayweg 4-6, 14195 Berlin

We study the mesoscopic ordering behavior of simple adsorbates from first-principles by parametrizing a lattice gas hamiltonian (LGH) with density-functional theory (DFT) data. Based on this LGH, subsequent Monte-Carlo Simulations provide the (T,p)-surface phase diagram, which enables us to systematically discuss the potential and limitations of this approach by comparing with corresponding experimental data. For O/Rh(111) the rather large binding energy variations with coverage lead to a rapid convergence of the LGH expansion. The subtle energy differences involved in the hydrogen bonding at surfaces on the other hand provide a critical test case. Only after including more than 15 lateral, up to quattro interactions we obtain very good overall agreement with the experimental phase diagram for H/Pd(111), reproducing the critical temperatures of the two ordered overlayers within 20K.

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