Self-consistent GW determination of the interaction strength: Application to the iron arsenide superconductors

We introduce a first principles approach to determine the strength of the electronic correlations based on the fully self-consistent GW approximation. The approach provides a seamless interface with dynamical mean field theory, and gives good results for well studied correlated materials such as NiO. Applied to the recently discovered iron arsenide materials, it accounts for the noticeable correlation features observed in optics and photoemission while explaining the absence of visible satellites in x-ray absorption experiments and other high energy spectroscopies.