Electron and Phonon States in Thin Crystalline Films

The dispersion law for electrons and phonons in thin crystalline films was evaluated using the method of two-time temperature dependent commutator and retarded Green’s functions. The conditions for the appearance of the localized states were studied by the numerical analysis of the spectra of these excitations for given boundary parameters (perturbed by the presence of boundaries). After determining the distribution of the density of states, it was concluded that these are surface states and that their energy and their population depend strongly on the values of boundary parameters.