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O: Oberflächenphysik
O 38: Adsorption V
O 38.7: Vortrag
Donnerstag, 30. März 2006, 16:30–16:45, TRE Phys
Adsorbate Properties of single PTCDA-Molecules on Ag(111) — •Rolf Öttking1, Werner A. Hofer2, Wichard J.D. Beenken1, Erich Runge1, and Juergen A. Schaefer1 — 1Institut für Physik und Zentrum für Mikro- und Nanotechnologien, Technische Universität Ilmenau Postfach 100565, 98684 Ilmenau — 2Surface Science Research Centre, The University of Liverpool, Liverpool L69 3BX
We present structural, charge and bonding properties of the initial adsorbation state of the organic molecule (3,4,9,10)-perylene-tetracarboxylic dianhydride (PTCDA) on highly coordinated silver Ag(111) surfaces derived from first-principles- (DFT-) calculations using projector-augmented waves (PAW-) pseudopotentials and a plane wave basis set. The substrate was taken to be a 11.5Å×20.0Å4-layer slab with the PTCDA- adsorbate with dimensions of ∼11.3Å×6.8Åplanarly placed on top. After structural relaxation, performed along the Hellmann-Feynman-Forces, the molecule shows a bent structure with radius of curvature of ∼20Å. The oxygen-atoms point downwards with a height difference of ∼0.17Åto the silver surface plane between the carboxylic (corner) and the anhydride oxygen atoms. From a Bader analysis we derive a net charge transfer of ∼1 electron charge from delocalised states of the two topmost silver layers into the adsorbate LUMO. In addition, binding orbitals and Ag 3d5/2 core level shifts were determined.