Theoretical study of F-type color center in rutile TiO2

The embedded-cluster numerical discrete variational method has been developed to investigate electronic structure of F-type color center in rutile TiO2(F-, F+- and F2+-centers). In the calculation, the lattice relaxation of ion around the vacancy has been discussed by calculating the lowest total energy of the cluster system. The polarization effect induced by the color center was included besides the coulomb and exchange potential. The excited energy of color center electron was treated by transition state method. A comparison between calculated results and optical experimental results confirms that the 760 nm peak is attributed to F+-center, 1.7 mum is attributed to F-center, and the transformation of F --> F+ center exists. Meanwhile, the semi-conductive property of annealed rutile is due to the existence of F-type color center. (C) 2001 Elsevier Science Ltd. All rights reserved.