Normal-state correlated electronic structure of iron pnictides from first principles

We describe the correlated electronic structure of a prototype Fe-pnictide superconductor, SmO_1−xF_xFeAs, using local-density approximation plus dynamical mean-field theory. Strong, multiorbital electronic correlations generate a low-energy pseudogap in the undistorted phase, giving a bad, incoherent metal in qualitative agreement with observations. Very good semiquantitative agreement with the experimental spectral functions is seen (for U=4.0 eV and J_H=0.7 eV) and interpreted within a correlated, multiorbital picture. Our results show that Fe pnictides should be understood as low-carrier density, incoherent metals, in resemblance to the underdoped cuprate superconductors.