Ab initio Calculations of Bulk and (001) Surface F-centers in ABO3 Perovskites

We analyzed systematic trends in BaTiO
₃
, SrTiO
₃
, PbZrO
₃
and SrZrO
₃
bulk as well as very rarely performed (001) surface F-center ab initio calculations. The nearest neighbor atomic displacements around the bulk F-center in the ABO
₃
perovskites are considerably smaller than the relevant neighbor atomic displacements around the (001) surface F-centers. The F-center electrons are more delocalized for the ABO
₃
perovskite (001) surface F-center than for the bulk F-center. Our calculated formation energy differences between the BaTiO
₃
, SrTiO
₃
, PbZrO
₃
and SrZrO
₃
bulk and its (001) surface F-centers triggers the F-center segregation from the bulk crystal towards the ABO
₃
perovskite (001) surface.