Theoretical electronic properties of TiO2(rutile) (001) and (110) surfaces

Abstract

We have calculated the one-electron density of states of thick slabs of Ti${\mathrm{O}}_2$ (rutile) with (001) and (110) symmetry using the linear combination of muffin-tin orbitals (LCMTO) energy-band method. We have also calculated the density of states of bulk Ti${\mathrm{O}}_2$ and of bulk ${\mathrm{Ti}}_2$ ${\mathrm{O}}_3$. We found that the local titanium-oxygen coordination is the major factor determining the band structures of these surface and bulk systems. In particular, for the unreconstructed (001) face of Ti${\mathrm{O}}_2$, we found that there is a large band of occupied surface states in the bulk band gap while there are no occupied states for the unreconstructed (but slightly relaxed) (110) surface. Our results suggest that the (001) face reconstructs to increase the local coordination of titanium in order to eliminate these band-gap surface states.