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O: Fachverband Oberflächenphysik

O 35: Poster Session I (Metal, semiconductor and oxide substrates: structure and adsorbates; Graphene)

O 35.29: Poster

Dienstag, 12. März 2013, 18:15–21:45, Poster B1

Comparative study of periodic and non-periodic approaches: Organic π-systems on coinage metals. — •Jaita Banerjee and Reinhold Fink — Institut für Physikalische und Theoretische Chemie, Universität Tübingen, Germany

We present a comparative study of metal-organic interface properties obtained from DFT calculations based on two different approaches: the periodic slab supercell technique and the cluster ansatz. Such interfaces of aromatic organic molecules with metal substrates form one of the important parts of organic optoelectronic devices. While it is well established that plane waves-pseudopotentials-periodic supercell approaches are reasonable methods to study the geometric and electronic structure of such interfaces, the cluster ansatz has not been much studied. We choose two different π-systems on silver and gold surfaces respectively. The strategy has been to obtain the structure and energetics of each system using the periodic supercell approach, then constructing the metallic clusters from the obtained periodic results. After optimizing the metal clusters, the molecule is placed on its surface and the respective adsorption energies and distances are computed. Our results indicate that while small clusters consisting of two metallic layers form unsuitable systems, clusters with 4 layers begin to show trends as obtained from the periodic calculations. The effect of van der Waals dispersion is also included. Our findings encourage possibilities of using the cluster ansatz to study molecule-metal interfaces since often the size of the organic molecule poses computational challenges in performing a full periodic calculation.