Phys. Rev. B 73, 075430 (2006) (11 pages)

Unusual adsorption site of hydrogen on the unreconstructed Ir(100) surface

D. Lerch, A. Klein, A. Schmidt, S. Müller, L. Hammer, and K. Heinz

Lehrstuhl für Festkörperphysik, Universität Erlangen-Nürnberg, Staudtstrasse 7, D-91058 Erlangen, Germany

M. Weinert

Department of Physics, University of Wisconsin–Milwaukee, P.O. Box 413, Milwaukee, Wisconsin 53201, USA

(Received 22 November 2005; published 23 February 2006)

The adsorption of hydrogen on the metastable, unreconstructed Ir(100)-(1×1) surface is investigated by density functional theory (DFT), quantitative low-energy diffraction (LEED), and thermal desorption spectrometry (TDS) complemented by scanning tunneling microscopy (STM). The bridge site is unequivocally identified as the adsorption site, rather unusual for metallic fcc(100) surfaces. There is excellent quantitative agreement between calculated and experimentally determined structural parameters both for the clean surface and the adsorbate covered surface. Given the uncertainty of DFT to reproduce absolute energies there is also good agreement with the measured adsorption energy (460  meV/atom). Additionally, theoretical vibrational and electronic properties are provided without, however, related experiments being available.