There are two advantages of using Eq. ( ) over direct integration of Eq. ( ). Firstly, it offers significant reduction in the overall simulation time compared to full propagation of the density matrix along the entire sampling time. Secondly, long sampling times of up to milliseconds are required to accurately simulate 2 H NMR lineshapes, which is impractical for many MD simulations. The use of Eq. ( ) allows predictions of NMR data from relatively short MD trajectories (up to the point when autocorrelation functions of rotational dynamics are fully relaxed) . As discussed in Section 5 of the Supplementary Information, this approach is also distinct from simulations of intermediate timescale dynamics in 2 H NMR using Markov models.