High-precision molecular dynamics simulation of UO2-PuO2: Anion self-diffusion in UO2

► We perform MD simulation of oxygen diffusion in UO2 (up to 50 000 ions and 1 μs time). ► We reached 1400 K and 10−12 cm2/sec, which allowed direct comparison to experiments. ► S-shaped T-dependence of activation energy and λ-peak of its derivative were obtained. ► Continual superionic phase transition (rather than first or second order) was proved. ► Activation energy of exchange diffusion equals anti-Frenkel defect formation energy.