Fig. 2: Interfacial electric fields for pure water droplets.

A Cumulative charge density using the ReaxFF/C-GeM model. The inset shows a cross-section of the droplet with a 40 Å radius with the surface waters depicted in gray as measured for the instantaneous surface. The green dotted lines pertain to definitions of L0 and L1 regions. B The variations in surface potential by radial regions in the R40 water droplet. C Inner water droplet contributions to the electric field at the surface are negligible and show a Gaussian distribution. D Electric field distributions at the surface are seen to be Lorentzian as measured over L0-L1. The electric field is largest in the normal direction to the interface. Here we use a grid resolution of 1.0 Å, although the results are the same with a finer 0.25 Å resolution (see Supplementary Fig. 4A).