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MM: Fachverband Metall- und Materialphysik
MM 39: Computational Materials Modelling V
MM 39.8: Talk
Thursday, March 17, 2011, 18:00–18:15, IFW A
TDDFT study of the momentum-dependent loss function of palladium — •Stephan Sagmeister1, Kathrin Glantschnig1, Gerald Kothleitner2, Cecile Hebert3, and Claudia Ambrosch-Draxl1 — 1Chair of Atomistic Modelling and Design of Materials, University of Leoben , Austria — 2Institut für Elektronenmikroskopie und Feinstrukturforschung, TU Graz , Austria — 3Ecole Polytechnique Federale de Lausanne (EPFL) (Institute of Condensed Matter Physics) , Switzerland
The momentum-dependent loss function of several bulk metals, including palladium, is investigated by means of time-dependent density functional theory (TDDFT) as well as experimental data based on EELS (electron energy loss spectroscopy) measurements. On the theoretical side, density-functional theory within the full-potential LAPW (linearized augmented planewave) method is employed to obtain the Kohn-Sham band structure, using the exciting code. The framework of TDDFT is utilized within the linear response regime for the calculation of the macroscopic dielectric function and hence the loss function, including crystal local-field effects. The loss function is studied as a function of momentum transfer q for several directions in the Brillouin zone. While TDLDA, or even the independent-particle approximation, can well reproduce the low energy range, for higher energies local-field effects become crucial. For the case of Pd this is reflected in the spectra within the range of 40 to 60 eV, where the local-field effects can reduce the spectral weight by up to 50%. The calculations are in excellent agreement with experimental data.