Berlin 2005 – wissenschaftliches Programm

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O: Oberflächenphysik

O 36: Postersitzung (Elektronische Struktur, Grenzfl
äche fest-flüssig, Halbleiteroberfl
ächen und -grenzfl
ächen, Nanostrukturen, Oberfl
ächenreaktionen, Teilchen und Cluster, Struktur und Dynamik reiner Oberfl
ächen)

O 36.11: Poster

Montag, 7. März 2005, 15:00–18:00, Poster TU F

GW quasiparticle calculations for surfaces: the role of periodicity in the repeated-slab approach — •Christoph Freysoldt¹, Philipp Eggert¹, Patrick Rinke¹, Arno Schindlmayr^1,2, and Matthias Scheffler¹ — ¹Fritz-Haber-Institut der Max-Planck-Gesellschaft, Faradayweg 4-6, 14195 Berlin, Germany — ²Institut für Festkörperforschung, Forschungszentrum Jülich, 52425 Jülich, Germany

Many-body perturbation theory in the GW approximation has become a valuable tool for ab-initio band structure calculations that are typically in good agreement with photoelectron experiments. In order to treat surfaces one often employs a repeated slab geometry for computational convenience. If no low-order electric multipole moments are present in the slab, the limit of the isolated slab is quickly reached when increasing the slab separation. Within GW, multipoles are induced even if the ground state exhibits no dipole which may lead to slower convergence compared to DFT. We show that certain approximations that are commonly made in GW implementations must be carefully validated in order to capture the physical behaviour of the repeated slabs. Our numerical results give evidence that the periodic arrangement manifests itself noticeably in the bandstructure, which is in agreement with an electrostatic model that incorporates the induced dipole effects. Prospects for realistic GW surface calculations are discussed.