Even if the degree of concerted motion is not increased by faster reorientation, it might be expected that diffusivity along to the GB plane is faster than diffusivity through the GB. However, we find that the difference in activation energy parallel and perpendicular to the GB plane is rather small (Figure ). The paddle-wheel effect has also been proposed to enable concerted motion. By calculating the distinct part of the van Hove correlation function, G d (r, t), at 800 K for Li Transport in the bulk of Li 3 OCl does not exhibit strong correlation, with a large value of t c = 8.9 ps. For both the Σ3{112} and Σ5{310} GBs, the timescale of correlation is vastly increased to far beyond the 15 ps time window for which we have calculated G d (r, t) (see Supplementary Information Figure ). Li 2 OHCl also shows little correlated motion, with neither the bulk nor either GB having a correlation timescale within the 15 ps window. In Li 3 PS 4 , we see much more strongly correlated motion in the bulk of the material with t c = 3.7 ps, with the Σ3{121} and Σ5{210} GBs having increased correlation timescales of around 7.1 ps and 11.7 ps, respectively. For bulk Li 3 InCl 6 , we find a higher correlation timescale of 6.3 ps, sitting roughly in the middle of of bulk Li 3 PS 4 and Li 3 OCl, but the presence of GBs has no real impact on t c , with the Σ3{112} and Σ5{310} GBs having timescales of around 6.1 ps and 6.8 ps, respectively (Figure ), which is perhaps not surprising given the lack of impact the GBs have on diffusivity at these temperatures.