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HL: Halbleiterphysik

HL 28: Gitterdynamik

HL 28.7: Talk

Thursday, March 20, 1997, 12:00–12:15, H4

Lattice dynamics of wurtzite CdS: ab initio calculations and neutron scattering measuraments — •A. Debernardi¹, A. G"obel¹, T. Ruf¹, R. Lauck¹, M. Cardona¹, S. Kramp², and N. Pyka² — ¹Max-Planck-Institut f"ur Festk"orperforschung Heisenbergstrasse 1, 70569 Stuttgart — ²Institut Laue-Langevin, Science Division, B.P. 156 F-38042 Grenoble Cedex 9, France

We present the results of our calculation on phonon dispersion branches of wurtzite CdS obtained by Density-Functional Perturbation Theory, One of the two silent modes occurs at 3.96 THz (q=0) and is significantly lower and less dispersive than previously assumed. We compare our theoretical data with experimental phonon frequencies we have obtained by inelastic neutron scattering in a single crystal made from the non-adsorbing isotope ¹¹⁴Cd. The computed dielectric constants, effective charges and related quantities are presented and compared with available experimental data.