Comparison of standard DFT and Hubbard-DFT methods in structural and electronic properties of TiO2 polymorphs and H-titanate ultrathin sheets for DSSC application

The structural and electronic properties of several TiO2 polymorphs and hydrogen titanate surfaces are modeled and studied by density functional theory (DFT). By implementing the Hubbard parameter “U” in our calculations more realistic results of electronic properties are obtained, paying with a small deviation in geometric optimization. Lattice parameters difference is found to be less than 6.2%, as well as some changes in surface energy are found, but the reactivity tendency of surfaces is maintained. Calculated work function is less energetic for faces (001) for anatase, (101) for rutile and (001) for TiO2-B.