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O: Fachverband Oberflächenphysik

O 60: Poster Session IV (Solid/liquid interfaces; Semiconductors; Oxides and insulators; Graphene; Plasmonics and nanooptics; Electronic Structure; Surface chemical reactions; Heterogeneous catalysis)

O 60.25: Poster

Wednesday, March 16, 2011, 17:30–21:00, P4

Organic Molecules on Wide-Gap Insulating Surfaces from First-Principles — •Wei Chen, Karthiga Kantasamy, Christoph Tegenkamp, and Herbert Pfnür — Institut für Festkörperphysik, Leibniz Universität Hannover, 30167 Hannover, Germany

We investigate the adsorption of benzoic acid and its various phenolic derivatives on wide-gap insulators (e.g. NaCl and KCl surfaces) from first-principles, in an effort to demystify the contact charging effect between salt mines mixed with organic molecules. While Kohn-Sham density functional theory (KS-DFT) becomes a de facto standard for the predictions of ground-state properties, it is far from being perfect and the standard semi-local density functional approximations suffer from several limitations, such as the notorious gap problem and the neglect of the prevalent long-range van der Waals interaction in the weakly bonded systems. Moreover, the problem of electronic excitations are beyond the scope of KS-DFT. In this work, a variety of ab initio methods are adopted at the respective level of theory, from KS-DFT (with hybrid functionals and dispersion force corrections) to Hedin’s GW approximation and ultimately the two-particle Bethe-Salpeter equation. The important roles of the long-range correlations, surface defects and the excitonic effect are presented in the context of the molecule-insulator interfaces.