Regensburg 2007 – wissenschaftliches Programm

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O: Fachverband Oberflächenphysik

O 41: Metal Substrates: Adsorption II

O 41.7: Vortrag

Mittwoch, 28. März 2007, 17:15–17:30, H39

On the accuracy of first-principles lateral interactions: Oxygen at Pd(100) — •Yongsheng Zhang, Volker Blum, and Karsten Reuter — Fritz-Haber-Institut, Faradayweg 4-6, D-14195 Berlin, Germany

We employ a first-principles lattice-gas Hamiltonian (LGH) approach to determine the lateral interactions between O atoms adsorbed on the Pd(100) surface. With these interactions we obtain an ordering behavior at low coverages that is in quantitative agreement with experimental data. Uncertainties in our approach arise from the finite LGH expansion and from the approximate exchange-correlation (xc) functional underlying the employed density-functional theory energetics. We carefully scrutinize these uncertainties and conclude that they primarily affect the on-site energy, which rationalizes the agreement with the experimental data. We also investigate the validity of the frequently applied assumption that the ordering energies can be represented by a sum of pair terms. Restricting our LGH expansion to just pairwise lateral interactions, we find that this results in effective interactions which contain spurious contributions that are notably larger than any of the uncertainties e.g. due to the approximate xc functional.