and fit the resulting hACF C Q i over the stretched exponential given by Equation to extract a decay constant ⌧ and Li hopping rate ⌧ 1 . A histogram of all of the individual atomistic C Q values calculated using DFT on the -LPS training set is shown in Figure , right panel. The spread of C Q values for the LiS 6 sites is much wider than that for LiS 4 , and their averages are able to be discriminated (a 30 kHz difference). LiS 6 sites have an average CQ of 124.1 kHz, whereas LiS 4 sites have an CQ of 90.9 kHz . Thus while !Q cannot be used to distinguish these two sites, their CQ values could be a good target to understand the local structure in ideal single crystal -LPS. Using the UFP-MD, we are able to track single-atom trajectories across the simulation, and therefore can calculate a single-atom ACF C Q , for each site in the -LPS crystalline structure. In order to understand how the hACF C Q i behaves, we separate the individual single atom ACF C Q , by the Li sites at time t = 0. In Figure , we plot both the individual ACF C Q and hACF C Q i, where the individual ACF C Q are colored by the site in which the Li atom started at time t = 0. The hACF C Q i average is calculated over the 13 Li ions that experience a hop to a different site (either LiS 4 ! LiS 6 or vice versa) during the 1 µs simulation, to reduce the noise in the hACF C Q i. We show that averaging over only the sites which hop is a reasonable assumption to make by comparing these results to a 1 µs simulation at 350 K, shown in the Supporting Information Figure , in which 102 Li atoms hop during the simulation, and there is better averaging over more sites.