Green's-function calculation of surface properties associated with adsorption

A technique to calculate the single-particle Green's function, and therefore the density of states and other single-particle properties for surface phenomena, is described. The Green's function is constructed from two wave functions, solutions of the Schrödinger equation satisfying boundary conditions in the bulk and in the vacuum. We apply the technique to piecewise constant potential models, where the Green's function can be obtained in analytic form. Results for surface densities of states for these model potentials are presented.