Berlin 2005 – wissenschaftliches Programm
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O: Oberflächenphysik
O 28: Methodisches (Exp. und Theorie)
O 28.5: Vortrag
Samstag, 5. März 2005, 16:00–16:15, TU EB407
GW quasiparticle energy calculations for surfaces: the influence of dynamic polarization in a repeated-slab approach — •Philipp Eggert1, Christoph Freysoldt1, Patrick Rinke1, Arno Schindlmayr1,2, and Matthias Scheffler1 — 1Fritz-Haber-Institut der Max-Planck-Gesellschaft, Faradayweg 4-6, 14195 Berlin, Germany — 2Institut für Festkörperforschung, Forschungszentrum Jülich, 52425 Jülich, Germany
The combination of density functional theory (DFT) and many-body perturbation theory in the GW approximation has become an important tool for ab-initio band structure calculations typically in good agreement with experiment. In order to treat surfaces one often employs a repeated slab geometry for computational convenience. However, electric multipole moments may occur in the slabs which then lead to a slowly decaying electrostatic interaction. If present, static dipoles must be corrected for in DFT [1]. In GW however, dynamic dipoles are always created. We present calculations for the hydrogen-saturated silicon (001) slabs and show that slabs smaller than 10 layers are not converged fully with 10-20 Å vacuum thickness. The effect of the dynamic dipoles is slowly decreasing with slab thickness, in accordance with an extension of a simple electrostatic model, that includes these polarization effects [2]. Therefore it is essential to monitor the convergence carefully and if necessary to extrapolate to infinite separation.
[1] J. Neugebauer, M. Scheffler, Phys. Rev. B 46, 16067 (1992)
[2] C. Delerue, G. Allan and M. Lannoo, Phys. Rev. Lett. 90, 076803 (2003)