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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 36.29: Poster

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

Optically excited electronic states of the 2H:Si(001)-(2x1) surface — •Neng-Ping Wang¹, Michael Rohlfing¹, Peter Krüger², and Johannes Pollmann² — ¹School of Engineering and Science, International University Bremen, P.O. Box. 750561, 28725 Bremen, Germany — ²Institut für Festkörpertheorie, Universität Münster

We report on ab initio calculations for optically excited electronic states of the 2H:Si(001)-(2x1) surface. The ground-state geometry is addressed by DFT calculations within the local-density (LDA) and generalized gradient (GGA) approximation. Based on this, the optically excited electronic states are described by many-body perturbation theory (MBPT; GW approximation and Bethe-Salpeter equation). Of particular interest are dynamical processes within the excited states that lead to photodesorption of hydrogen atoms [see the experimental results by T. Vondrak and X.-Y. Zhu, Phys. Rev. Lett. 82, 1967 (1999)]. In this work, we try to explain the photodissociation of the adsorbate-surface bond within the framework of MBPT. This requires to calculate the corresponding excited-state forces. One particular issue concerns the local character of the excitation, which we describe by appropriate confinement potentials.