where 𝜃 w is the coverage of water molecules at the IHP which is taken as a constant here, 𝜇 w is the dipole moment of a water molecule, 〈cos α w 〉 is the statistical average of cos α w with 𝛼 w being the angle between water dipoles and the local electric field. Herein, a positive electric field points towards the bulk solution, and the direction of a dipole points from its negative end to its positive end.