Fig. 4: Cation hydration structures on vermiculite surface.

a, b Probability density plots for thin water films on vermiculite surfaces substituted with potassium and lithium, respectively. The y-axis zero is taken to be the mean z position of the vermiculite surface oxygen atoms. Grey dotted lines indicate the distinction between the first and second contact layers of water. Snapshots are included showing the simulated liquid films and vermiculite structures on the right-hand side. Oxygen atoms are shown in red, hydrogen in white, silicon in yellow, aluminium in pink, magnesium in purple, and lithium and potassium in cyan. c Angular orientation of water molecules in the first and second contact layers of water using the angle between the vermiculite surface normal and water O–H bonds (θ). Distributions for the first contact layer are shown with solid lines, dashed lines represent the second layer of water. d Angular orientations of water molecules using the angle between the plane through the water molecule and the basal plane of the vermiculite surface (φ). Distributions for the first contact layer are shown with solid lines, while the second contact layer is shown with dashed lines. All source data are provided as a Source Data file.