Validity of the Local Approximation in Iron- Pnictides and Chalcogenides
  We introduce a cluster DMFT (Dynamical Mean Field Theory) approach to study the normal state of the iron pnictides and chalcogenides. In the regime of moderate mass renormalizations, the self-energy is very local, justifying the success of single site DMFT for these materials and for other Hunds metals. We solve the corresponding impurity model with CTQMC (Continuous Time Quantum Monte-Carlo) and find that the minus sign problem is not severe in regimes of moderate mass renormalization. 
Patrick S\'emon, Kristjan Haule, Gabriel Kotliar
cond-mat.str-el