Oxygen vacancy diffusion in rutile was studied using Born-Oppenheimer molecular dynamics within the framework of the semi-empirical molecular orbital method. Migration of an oxygen vacancy from the rutile (110) surface towards the bulk was simulated. The metadynamics technique was used to accelerate the diffusion processes. Transition-state structures and activation energies for the diffusion processes were obtained. Rate constants and the time-scale of diffusion processes were estimated for various temperatures by using the calculated activation energy. It was found that the vacancies in the bulk were less stable than on the surface.

Molecular Dynamics Investigation of Oxygen Vacancy Diffusion in Rutile. Jug, K., Nair, N.N., Bredow, T.: Physical Chemistry Chemical Physics, 2005, 7[13], 2616-21