Dresden 2011 – wissenschaftliches Programm
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O: Fachverband Oberflächenphysik
O 36: Poster Session II (Metals; Nanostructures at surfaces; Surface or interface magnetism; Spin-Orbit Interaction at Surfaces; Electron and spin dynamics; Surface dynamics; Methods; Theory and computation of electronic structure)
O 36.116: Poster
Dienstag, 15. März 2011, 18:30–22:00, P4
Methane adsorption on graphene: Influence of dispersion interaction — •Matthias Witte1, Christian Thierfelder1, Stephan Blankenburg1,2, Eva Rauls1, and Wolf Gero Schmidt1 — 1Theoretische Physik, Universität Paderborn, 33100 Paderborn, Germany — 2Eidgenössische Materialprüfungs- und Forschungsanstalt (EMPA), 8600 Dübendorf, Switzerland
Van der Waals interaction is not properly described in density functional theory within commonly used exchange-correlation functionals. Therefore several semi-empirical and ab-inito solutions have been proposed and implemented in widely used program packages. Here we use the methane-graphene interaction as benchmark system to compare the results of semiempirical dispersion correction schemes (DFT-D) [1,2] and an ab initio van der Waals density functional (vdW-DF) ansatz [3]. Møller Plesset perturbation theory (MP2) [4] calculations are used as a reference. The adsorption energy of 0.17 eV and the molecular distance of 3.28 Å obtained from the MP2 calculations are close the experimental data, while the vdW-DF scheme results either in a realistic adsorption energy or a realistic adsorption geometry, depending on the exchange-correlation functional. The present implementation of DFT-D overbinds about as much as bare DFT calculations underbind, but yields a meaningful adsorption height. [1] F. Ortmann, W.G. Schmidt and F. Bechstedt, Phys. Rev. Lett. 95, 186101 (2005) [2] S. Grimme, J. Comp. Chem. 27, 1787 (2006) [3] M. Dion, H. Rydberg, E. Schröder, D.C. Langreth and B.I. Lundqvist, Phys. Rev. Lett. 92, 246401 (2004) [4] C. Møller and M.S. Plesset, Phys. Rev. 46, 618 (1934)