The structure of water at a planar wall: An integral equation approach with the central force model

The structure of liquid water in contact with a planar wall is calculated for the central force model by which water is modeled as a stoichiometric mixture of partially charged hydrogen and oxygen atoms interacting via effective spherical pair potentials. The density profiles near the wall are obtained from the Wertheim–Lovett–Mou–Buff equation extended to mixtures with coulombic interactions. The correlations in the bulk liquid are calculated by adding bridge functions of appropriate reference hard sphere systems to the hypernetted chain equation. We have obtained structural (stoichiometry, hydrogen bonds) and thermodynamic properties in good agreement with computer simulations. We also expose the water to electric fields due to a surface charge on the wall.