Electron states of iron group impurities in doped rutile (TiO₂)

The electronic structure of rutile, TiO₂, doped with iron-group ions was investigated using the embedded-cluster discrete variational method. The Ti⁴⁺ cation is substituted by iron-group impurity ions and the impurity-substituted cluster is embedded into the periodic crystal lattice of rutile. Numerical results were obtained for the energy bands, the density of states and the effective ionic charges. In particular, the impurity energy level scheme was found by using a non-empirical theoretical method for the first time. Compared with results from photocurrent measurements and optical absorption data, the impurity level scheme is in general agreement with experiments.