| Numéro |
J. Phys. Colloques
Volume 42, Numéro C6, Décembre 1981
International Conference on Phonon Physics
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|---|---|---|
| Page(s) | C6-834 - C6-836 | |
| DOI | https://doi.org/10.1051/jphyscol:19816246 | |
International Conference on Phonon Physics
J. Phys. Colloques 42 (1981) C6-834-C6-836
DOI: 10.1051/jphyscol:19816246
Max-Planck-Institut für Festkörperforschung, 7000-Stuttgart-80, F. R. G.
J. Phys. Colloques 42 (1981) C6-834-C6-836
DOI: 10.1051/jphyscol:19816246
MICROSCOPIC THEORY OF LATTICE DYNAMICS AND RECONSTRUCTION OF SEMICONDUCTOR SURFACES
A. Muramatsu et W. HankeMax-Planck-Institut für Festkörperforschung, 7000-Stuttgart-80, F. R. G.
Abstract
On the basis of a microscopic theory of surface density response including local-field and excitonic effects we calculate the phonon spectrum of an ideal Si(111) slab. A drastic enhancement of the non-local response is obtained for wavevectors corresponding to 2x1 and 7x7 superstructures, signalling an excitonic insulator instability of the metallic dangling bond surface state. The coupling of the resulting charge-density wave to the lattice produces a soft surface mode with atomic displacements supporting the ionic buckling model.