Investigation of various polymorphs of TiO₂ using the density functional theory plus U approach in all electron calculation

The method of density functional theory (DFT) combined with Hubbard U correction has been employed to wide-ranging applications in correlated systems. Although the DFT+U method can dramatically improve the treatment of many strongly correlated systems, a careful attention must be paid on those parameters that significantly influence results. In this study, we report a systematic investigation of the effect U on lattice parameters, electronic structure, and relative stability of TiO₂ among rutile, anatase, and columbite as the effective spatial range of local projection is varied using all-electron calculations. Our results show that substantially different results can be obtained due to different effective ranges of the local projection functions.