Surface excitons in molecular crystals: A theoretical approach

A theory is presented for the treatment of surface states in general molecular crystals. The perfect and surface crystal solutions are developed in terms of a common basis exploiting the common translational symmetry of all planes parallel to the crystal surface. The surface states are then determined in terms of the perfect crystal solutions using Greens' function methods. The theory is applied to the determination of the conditions under which localized surface states appear in crystals with one molecule per unitcell.