The Pd(100)-(√5 × √5)R27°-O surface oxide: a LEED, DFT and STM study

P. Kostelník1, N. Seriani2, G. Kresse2, A. Mikkelsen3, E. Lundgren3, V. Blum4, T. Šikola1, P. Varga5, M. Schmid5

1Institute of Physical Engineering, Brno University of Technology, 61669 Brno, Czech Republic
2Institut für Materialphysik and Center for Computational Materials Science, Universität Wien, 1090 Wien, Austria
3Department of Synchrotron Radiation Research, Institute of Physics, Lund University, 22100 Lund, Sweden
4Fritz-Haber Institut der Max-Planck-Gesellschaft, D-14195 Berlin, Germany
5Institut für Allgemeine Physik, Technische Universität Wien, 1040 Wien, Austria

Surf. Sci. 601 (2007) 1574-1581

Using low energy electron diffraction (LEED), density functional theory (DFT) and scanning tunneling microscopy (STM), we have re-analyzed the Pd(100)-(√5 × √5)R27°-O surface oxide structure consisting, in the most recent model, of a strained PdO(101) layer on top of the Pd(100) surface [M. Todorova et al., Surf. Sci. 541 (2003) 101]. Both, DFT simulations using the Vienna Ab-initio Simulation Package (VASP) and tensor LEED I(V) analysis of newly acquired LEED experimental data, show that the PdO(101) model is essentially correct. However, compared to the previous study, there is a horizontal shift of the PdO(101) layer with respect to the Pd(100) substrate. The atomic coordinates derived by DFT and LEED (RP = 0.162) are in excellent agreement with each other. We also present STM images with atomic resolution showing domain boundaries on the surface oxide and discuss the bonding geometry between the surface oxide and the substrate.

Corresponding author: M. Schmid (schmid< encoded email address >).

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