Molecular crystal surface dielectric properties: Microscopic theory for linear response

A microscopic molecular theory is developed for dielectric behavior at molecular crystal surfaces. Since dipolar interactions between layers of molecules decrease rapidly with separation, only layers within a short distance of the surface are affected by it. Algebraic results are obtained relating the local electric field and the macroscopic electric field in a surface layer to an applied uniform electric field, and hence to one another. These lead to expressions for the linear electric susceptibility of a layer and of an assembly of layers. The results provide a basis for calculations of various surface-induced and surface-modified properties.