Regensburg 2004 – scientific programme

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O: Oberflächenphysik

O 43: Adsorption an Oberflächen IV

O 43.8: Talk

Friday, March 12, 2004, 13:00–13:15, H36

Ab-initio investigation of the adsorption of H on the Ir(100) − 1× 1 surface — •Daniel Lerch, Stefan Müller, and Klaus Heinz — Festkörperphysik, Universität Erlangen-Nürnberg, Staudtstr.7, D-91058 Erlangen

The adsorption of H on the metastable Ir(100) − 1× 1 surface was studied via first-principles calculations, which reveal total energies as well as vibrational and electronic properties.

Since thermal desorption spectra give no hint that H does occupy subsurface sites, we focus on the site- and concentraction-dependence of the adsorption energy of H on the Ir(100) top layer. Our ab-initio DFT calculations (including vibrational zero-point energies) indicate that for all considered H-concentrations (0.25 – 2 monolayer) the bridge position is the energetically favoured adsorption site. At one monolayer coverage an adsorption energy of 610 meV per H-atom results. The energetic hierarchy of H-adsorbate sites considered is bridge, top and hollow position with the latter being less favoured by 160 meV and 353 meV, respectively.

These unexpected results for the adsorption site are discussed, also with respect to the electronic properties of the Ir(100) − 1× 1 surface.

This work is supported by Deutsche Forschungsgemeinschaft.