The thermodynamics and kinetics of the drift/diffusion of oxygen vacancy defects in rutile were simulated by using the density-functional based tight-binding method. Both static and dynamic simulations were performed. Results indicate that density-functional based tight-binding was well suited to examine the dynamic behavior of oxygen vacancies in TiO2. Detailed analysis showed that strong model size dependence in relative diffusion barrier heights between different diffusion processes required great care in defect diffusion simulations in TiO2. Thermodynamic results on the influence of an external electric field showed that, due to the large dielectric constant, the coulomb driving force on oxygen vacancy diffusion was very small. Dynamic simulation of the influence of electric fields on the diffusion required the use of advanced molecular dynamics acceleration schemes.

Dynamic Simulation of the Migration of Oxygen Vacancy Defects in Rutile TiO2. Knaup, J.M., Wehlau, M., Frauenheim, T.: Materials Research Society Symposium Proceedings, 2012, 1430, 123-8