Electronic structure of the CeO2(1Â 1Â 0) surface oxygen vacancy

The oxygen vacancy formation on the CeO2(1 1 0) surface has been studied by ab initio electronic structure calculations. Embedded-cluster calculations with explicit treatment of the electron correlation from Møller-Plesset perturbation theory (MP2) provide an alternative description of the surface O vacancy compared to previously reported periodic density functional theory (DFT) calculations. The electronic structure at the MP2 level shows a complete localization of the excess electrons on the two surface Ce ions neighboring the vacancy, contrary to the delocalized description seen in the periodic DFT calculations for the CeO2(1 1 0) surface (but more in line with DFT+U results recently reported for the partially reduced CeO2 bulk and (0 0 1)-surface). Our calculations predict a vacancy formation energy (3.1-3.3 eV at the MP2 level including basis set superposition error (BSSE) correction) and a geometric structure in qualitative agreement with the periodic DFT results, where the surface O ion next to the vacancy assumes a bridging position between the reduced Ce ions.