The work of the “Heat and Charge Transport” group concerns methodological development, code development, as well as applications to accurately compute, understand, and predict transport properties of materials. The reliable assessment of the electronic structure and of the inter-atomic interactions by the means of density-functional theory (in its various flavors and approximations) represents the base of our research. On top of that, we use electronic-structure theory to investigate the dynamic and thermodynamic characteristics of materials, such as elastic constants, free energies, and vibrational properties. Ab initio molecular dynamics plays a prominent role in our research, given that it enables us to reliably simulate the dynamics even at elevated temperatures, e.g., at and above 70% of the melting temperature, at which perturbative approaches would fail. With our methods we are able to accurately compute the electron-phonon and phonon-phonon coupling to all orders. This provides the route for the assessment of (electronic and vibrational) heat and charge transport phenomena.
Applications include technologically relevant high-temperature materials. For instance, we study the thermodynamic equilibrium and heat transport properties of Zirconia compounds, which are used in thermal barrier coatings to protect the underlying turbine components from the extreme temperatures generated during combustion. In close collaboration with experimental colleagues, we also investigate the charge and heat transfer properties of thermoelectric materials, such as skutterudites and clathrates. Unraveling the electronic and atomistic mechanisms that determine the thermoelectric efficiency of these materials is key to the development of novel and improved waste-heat recovery devices.
Software and method development is key to achieve the research goals of the group. In particular, we are involved in the advancement of the all-electron, full-potential electronic-structure code FHI-aims and have developed our own, Python-based framework FHI-vibes for the assessment of vibrational properties of solids.