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R. Moser:
"First-principles calculations of lattice thermal conductivity";
Betreuer/in(nen), Begutachter/in(nen): P. Mohn, C. Franchini; Institut für Angewandte Physik (E134), 2016; Rigorosum: 15.06.2016.

The technological motivation of the present thesis is to contribute to the optimisation of thermoelectric materials. The scientific and theoretical goal is to derive and calculate from first principles the thermal conductivity of lattice vibrations or phonons, κph, which enters in the denominator of the figure of merit. By reducing κph the figure of merit can be enlarged.
In this work an overview of the formulation of thermal transport in solids is given and how the lattice thermal conductivity can be calculated by utilising a first-principles ap- proach. For the lattice vibrations anharmonic terms have to be considered in order to ac- count for transport phenomena like the heat flow as expressed by κph. In addition other phe- nomena like thermal expansion can be treated with the same first-principles basic results. The general concept behind this is the quasi-harmonic model which converts temperature dependent properties into volume dependent quantities.