The central formula expressed in Eq.( ) contains the interplay between the diffuse layer, water molecules at the IHP, and adsorbed intermediates at the IHP. In this section, the theoretical analysis starts with a simple case without chemisorption, namely, 𝜃 𝑖 = 0 in Eq. (24). The focus is put on how chemical interactions between water molecules at the IHP and the metal influence the pzc, and furthermore how field-dependent reorientation of water molecules changes the C dl profile.