Transition Metal Doping Of Tio <sub> 2 </ Sub> Electronic Structure Of The First Principle

The electronic structure of rutile TiO₂ doped with transition metals was analyzed by ab initio band caculations based on the density functional theory by a supercell approach. First, using the generalized gradient approximation for the exchange-correlation potential , we optimize the ground state of TiO₂ in the rutile structure. The computational structural parameters are in good agreement with experimental values within 2%. The internal parameter u is equal to experimental value. The energy gap we get is 1.78eV, which is smaller than experimental value. From the analysis of the electronic structure of TiO₂, we find that the upper valance bands are composed mainly of 0 2p states hybridized with Ti 3d states. The bandwidth of 5.65eV is in good agreement with experimental XPS and UPS measurements. Then we calculate the electronic structure after doping with different transition metals in TiO₂. The caculation shows that doping of the rutile model with Zr doesn't have a noticeable effect on the size of the rutile band gap. When TiO₂ is doped with V , Mn , Ru or Rh , a electron occupied level occurs and the rutile band gap is narrowed. The t_2g state of the dophant plays a significant role in the red shift and the photoresponse of TiO₂ under visible light irradiation. The V t_2g state is near the bottom of the conduction bands. The electron can hop from the top of the valance bands to the dophant. The Rh t_2g state is near the top of the valance bands. The electron can hop from the dophant to the conduction bands. The doping of TiO₂ with Mn or Ru is different from the doping of V or Rh. The t_2g state is in the band gap of TiO₂. Firstly, the electron can hop from the top of the valance bands to the dophant, then it keeps on hopping from the top of the dophant to the conduction bands.