where TC is the onset temperature of motional narrowing in Kelvin. A drawback of the W.-F. approach is the difficulty to estimate the exact onset of motional narrowing. We observe the onset of narrowing at ~180 K and from the W.-F. expression we obtain an activation energy of 0.29 eV. Generally, Li NMRmeasurements also capture Li motion that does not effectively contribute to macroscopic diffusion such as locally-confined diffusion and "back and forth" jumps. Activation energies obtained from DJ values thus better match activation energies obtained from Li NMR-measurements than activation energies obtained with Dtr values. The activation energies obtained from the H.-B. and the W.-F. expressions and the activation energy obtained from the DJ values in our AIMD simulations are all in a range between 0.21 eV and 0.29 eV (Table ). Generally, at temperatures below the onset of line narrowing the jump frequency is lower than the rigid-lattice-regime NMR line width. At temperatures where narrowing is observed the jump frequency is higher than the rigid-lattice-regime NMR line width. When extrapolating the jump frequencies obtained from AIMD simulations to temperatures of the rigid-lattice regime (<150 K) we indeed obtain jump frequencies lower than the rigid-lattice-regime NMR line width of 10 kHz.