Microscopic mechanisms of proton diffusion in the protonic conductor, Sc-doped SrTiO3, were studied using a first-principles molecular-dynamics simulation. It was shown that the proton formed an O-H bond with a neighboring O ion, and the frequency of the stretching vibration of the O-H bond was about 2800/cm; which agreed reasonably well with the results of experiment. Two types of diffusion paths were observed: one was diffusion around the O ion while retaining the O-H bond, and the other was diffusion between the two neighboring O ions while switching the O-H bond. During the former type of diffusion, stretching vibration occurred and the length of the O-H bond was almost unchanged. The latter type of diffusion occurred frequently and quickly.

First-Principles Molecular-Dynamics Simulation of Proton Diffusion in Sc-Doped SrTiO3. Shimojo, F., Hoshino, K., Okazaki, H.: Journal of the Physical Society of Japan, 1997, 66[1], 8-10. See also: Journal of Physics - Condensed Matter, 1998, 10[2], 285-94