Electron localization in pure and defective ceria by a unified LDA+U approach

The electronic and structural properties of pure and defective cerium oxide are investigated using a unified LDA+U approach which allows to treat the different valence states of Ce occurring for different stoichiometries on a same ground, without any {\it a priori} assumptions on the defect chemistry. The method correctly predicts the atomistic and electronic structures of the \4ce and \3ce bulk phases, as well as the subtle defect chemistry in reduced materials \xce, which controls the oxygen storage functionality of cerium-based oxides. The analysis of the energetics highlights the limits of the LDA+U method and possible extensions are proposed.