Electronic Structure of Fe-based Superconductors

Understanding the electronic structure and electronic interactions in the layered Fe superconductors is prerequisite to understanding their superconductivity and other properties. The purpose of this talk is to overview results obtained within band structure approaches in relation to experiment. So far, many puzzles remain. The materials appear to be much more band-like and show much stronger signatures of metallic (Fermi surface related) physics than cuprates, with correspondinly weaker signatures of on-site Hubbard correlations. However, there remain substantial discrepancies between bare band structure calculations and experiment, and interestingly these discrepancies are in the opposite direction from those found in cuprates. These are discussed in the context of spin-fluctuations. This work was done in collaboration with I.I. Mazin, M.H. Du, Lijun Zhang, Alaska Subedi and Michelle Johannes.