We assessed the two limits of overall microstructure in the LPS fast ion conductors. The -LPS crystal represents an infinitely large fully uniform single crystal of LPS, as depicted in orange in Figure . As such, all the ! Q values in both LiS 4 and LiS 6 sites have the same predominant value (c.f Figure left), which does not vary throughout the simulation, even during Li hopping events. In addition, the mean !Q for LiS 4 and LiS 6 are only 4 kHz apart, and the spread of the individual atomic ! Q for LiS 6 is entirely contained within the distribution for LiS 4 , as presented in Figure . Therefore, we would expect a vanishingly small decay of hACF ! Q i for single crystal -LPS, in which only those two sites are accessible, and then observe a residual, partially averaged coupling throughout. However in a polycrystalline material, shown in green in Figure , where LiS 4 and LiS 6 sites are oriented along different crystal axes in neighboring grain boundaries, we are no longer limited by the predominant orientation of the ideal single crystal. In this case, we would expect lower ⌧ SAE , and a better sensitivity to inter-grain Li-ion motion for SAE.