3. Theoretical study of electron structure and property of complex materials

(B. Hellsing, M. Granath, H. Johannesson, G. Wahnström)

The underlying physics explaining properties of several materials of technological interest is still not well understood. For some materials with a mix of delocalized and localized electrons, electron correlation is complex. For these materials, with electrons occupying active 3d, 4f or 5f orbitals, the Density functional theory (DFT), which is based on a static mean field description of the electron exchange and correlation, is not appropriate. The excitation spectra in these strongly correlated materials is traditionally described by model hamiltonians, such as the Hubbard model. However, a recently developed computational scheme to handle these systems has been developed, the Dynamical mean field theory (DMFT). It is of interest to apply DMFT to systems presently investigated by the project members, for example layered metallic materials, high-temperature supercondoctors, complex metal oxides, metal oxide interfaces and nano structures on surfaces. As DFT is demonstrated to give a poor description of the electron structure and related properties for several complex materials it is highly motivated to join the theoretical experties in the research groups Materials & surface physics (GU and Chalmers) and Condenced matter theory (GU) and learn about DMFT and similar techniques aimed at strongly correlated systems. DMFT is a hybrid between a DFT and a model hamiltonian approach and the project members represent experience from both ends, DFT (Hellsing and Wahnström) and model hamiltonian (Johannesson ond Granath). A new PhD student would be a good start to initiate a new type of research activity in theoretical material physics at the Physics Center of Göteborg (GU and Chalmers).