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SYEC: Symposium Exact-exchange and hybrid functionals meet quasiparticle energy calculations

SYEC 3: Exact-exchange and hybrid functionals meet quasiparticle energy calculations III - Poster (joined by SYMS posters)

SYEC 3.7: Poster

Donnerstag, 28. Februar 2008, 18:30–19:30, Poster F

Physisorption of Organic Molecules on Noble-Metal Surfaces — •Michael Rohlfing¹, Thomas Bredow², and Florian Janetzko² — ¹Fachbereich Physik, Universität Osnabrück, Germany — ²Institute for Physical and Theoretical Chemistry, Universität Bonn, Germany

We discuss the physisorption of organic molecules to noble-metal surfaces due to Van-der-Waals interaction. Different from density-functional theory, we treat the exchange energy explicitly and calculate the correlation part within the random-phase approximation. In here, the response of the metal surface is described by a combination of a jellium surface and local polarizability of the d electrons, while the response of the adsorbate is obtained from a DFT calculation. We discuss results for the adsorption of Xe, benzene, and PTCDA on the Ag(111) surface. The obtained adsorption energies and distances are between those of DFT-LDA (which overbinds) and DFT-PBE (which does not bind at all), thus constituting a significant improvement beyond DFT. The correlation energy obtained with RPA is compared to classical R⁻⁶ correction terms. Although the empirical approach gives qualitatively similar potential curves, RPA better reproduces experimental adsorption energies and distances.