Excitation spectra of coupled metallic slabs

The polarisability of the system consisting of two parallel thin metallic slabs within the jellium model is obtained within the assumption that the electron densities of the slabs do not overlap. It is then used to calculate, for the first time, the excitation spectra and dispersion relations of the collective surface excitations of that system. The dispersion relations are compared with the classical ones to enable the classification of the excitation modes.