(a) (b) The parameters (l in q l and τ ) required for accurate identification of crystalline and glassy PS 4 3units were optimized using CMD data for bulk β-Li 3 PS 4 and 75Li 2 S-25P 2 S 5 glass at 500 K. The distributions of the q l parameter derived from all PS 4 3units in bulk 75Li 2 S-25P 2 S 5 glass and β-Li 3 PS 4 were calculated with variables τ and l. For perfect classification, these distributions should be separated by a threshold without overlap.