First-Principles Study on Rutile TiO2 Quantum Dots

The electronic structure of rutile TiO 2 quantum dots (QDs) are investigated via the first-principles band structure method. We first propose a model to passivate the rutile TiO 2 surfaces for the local density approximation calculations. In this model pseudohydrogen atoms are used to passivate the surface dangling bonds, which remove the localized in-gap surface states in the TiO 2 QDs. As the size of the QD decreases, the band gap evolves as E g (dot) = E g (bulk) + 73.70/ d 1.93, where E g (dot) and d are the band gap and diameter of the QD, and E g (bulk) is the band gap of the bulk rutile TiO 2 . The valence band maximum and the conduction band minimum states of the QDs are distributed mostly in the interior of the QDs, and they well inherit the atomic characteristics of those states of the bulk rutile TiO 2 .