Fig. 4. (a) Contributions to the configurational excess entropy obtained from the radial distribution function (angular disorder is not considered). Spatial distribution functions showing the coordination of anions around cations are shown in (b) for [P(3O1)₄][BF₄] and (c) for [P5555][BF₄]. The isosurface is drawn at 10 mJ mol⁻¹ K⁻¹ Å⁻³.