Theoretical study of the Fluorine doped anatase surfaces

A systematic theoretical study based on periodic density functional theory (DFT) calculations using GGA and GGA+U approaches has been carried out to establish the thermodynamic stability of O by F substitution on the (001) and (101) surfaces of anatase. All calculations consistently predict that for both surfaces F implantation is more favorable at surface sites than at subsurface sites. However, the absolute value of the implantation energy has been found to largely depend on the density functional. This fact has strong implications in the study of doped oxides for those cases where accurate values of substitution energies are required.