A theoretical mixed classical/quantal model for describing the optical properties of free and matrix-embedded metal clusters, based on the time-dependent local-density approximation, is presented. As compared to the previous models involving an inner or/and an outer dielectric medium, all the dielectric effects—screening and absorbing properties—are self consistently calculated. Especially, the interband transitions, which dominate the absorption spectra in the UV spectral range, and the mutual interplay between the conduction and core electron excitations, are correctly taken into account.

• Received 14 May 1999

DOI:https://doi.org/10.1103/PhysRevB.60.16151