[Ifeffit] Peak assignment and ionization potential with FEFF

Hi everyone, Does anyone know whether FEFF can be used to assign peaks? In other words, is there a way to tell which peaks in a calcite O K-edge spectrum are due to CO bonds and which to CaO bonds? Also, does FEFF calculate the ionization potential and if so, where does it output this? Thanks! Ross DeVol University of Madison-Wisconsin