By calculating hACF ! Q i in both -and am-LPS, we find that the decay time for Li in am-LPS at 300 K is on the order of 46 ns, while the hACF ! Q i of single-crystalline -LPS exhibits no characteristic exponential decay, and instead oscillates about an average value of hACF ! Q i. By considering the orientations of the EFG tensors during the simulations in both -LPS and am-LPS we can see more clearly the differences in behavior of the EFG tensor in these two materials. Figure shows a 2D histogram of all of the accessed angles during the full 1 µs simulation at 300 K for -and am-LPS. In the -LPS histogram (Figure left), the majority of the angles (✓, ) are clustered around either (⇡/2, 0) for LiS 4 tetrahedra or (⇡/2±⇡/6, ±⇡/4) for LiS 6 . On the other hand, there are no clear preferred values of (✓, ) for am-LPS, indicating that the Li atoms experience a wide array of environments during the 1 µs simulation. The large spread in angular distribution in the am-LPS case is what leads to the characteristic rapid decay shown in Figure , as the Li ions visit sites with all possible orientations during the full simulation, leading to loss of correlation, which is normally characteristic of SAE in glasses or polymers . Once Li atoms are in a single crystalline grain, this orientational memory loss is no longer possible, and we see slow, or non existent decay as in -LPS.