Our DFT-AIMD simulations were performed in a canonical (N , V , T ) ensemble. The temperature in the AIMD simulations is kept fluctuating around a given value by using the Nose-Hoover thermostat. A 4 × 4 × 4 supercell was chosen with the Brillouin zone sampled only at the Γ-point. For these AIMD simulations, the plane-wave energy cutoff was reduced to 300 eV to lower the computational cost. We performed simulations at 300 K, 400 K, 500 K, 600 K and 678 K. At each temperature, we performed 10 independent AIMD simulations with different random seeds. Each simulation was run for 8000 steps with a timestep δt = 2 fs. We exclude the first 300 steps of each simulation to allow equilibration, giving a total of 154 ps of independent trajectory data at each temperature. Mean-squared displacements were cal-