Consideration of the spontaneous polarization of water at the solid/liquid interface

The orientation of water molecules close to a hard wall is studied. A simple model of water near interfaces is proposed in which only the hydrogen bond interactions among molecules and steric restrictions imposed by the wall are taken into account. The average number of hydrogen bonds per molecule is determined as a function of the distance from the interface. It is shown that a water molecule exhibits a preferred orientation at the surface because of its asymmetric character. Angular distribution of water molecules at the interface is studied by considering the effect of steric restrictions and orientational dependence on hydrogen bond probability. The magnitude of the resulting average polarization is estimated. The corresponding surface electrostatic potential is evaluated.