Berlin 2012 – scientific programme

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MM: Fachverband Metall- und Materialphysik

MM 45: Computational Materials Modelling VI - Thermal Conductivity and Transport

MM 45.3: Talk

Thursday, March 29, 2012, 10:45–11:00, TC 006

Thermal Conductivity in Ge-based Clathrate Systems — •Daniel Schopf and Hans-Rainer Trebin — Institut für Theoretische und Angewandte Physik, Universität Stuttgart

Intermetallic clathrates are currently actively investigated due to their special thermoelectric properties. They are composed of periodically arranged cages, formed by host atoms, which enclose single guest atoms. The low thermal conductivity of these structures has been attributed to the scattering of the phonons on the local vibration modes (``rattling'') of these guest atoms.

For computational studies of dynamic properties long simulation times and large samples are required. This makes first principle calculations of these structures, even with high performance computers, very unfeasible. Classical molecular dynamics, however, can meet the requirements. The potentials needed for these MD simulations can be obtained from ab-initio calculations with the force-matching method. It uses large numbers of reference data to fit an effective potential that reproduces the forces, energies and stresses of the ab-initio calculation.

To model the strongly directional atomic interactions in clathrates, angular dependent potentials are required. An analytic potential will be presented. With this potential and the Green-Kubo method, the thermal transport in different Ge-based clathrate systems has been investigated.