Electron density of states in disordered systems

A theoretical approach to the problem of the knowledge of the one-particle Green's function of a disordered system is proposed. By means of the Gubanov change of coordinates, the Green's function which is written in terms of moments of the density of states can be expressed as the sum of a 'periodic' Green's function and a perturbative term. Advantage is also taken of the recursion method in order to write the Green's function of the disordered system in the same form as recently proposed for the density of states in the case of a substitutional impurity.