Dielectric screening effects on the photoabsorption cross section of embedded metallic clusters

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Abstract
The surface plasmon resonance of alkali-metal (potassium) and noble-metal (silver) clusters embedded in different dielectric matrices is studied within the time-dependent density-functional formalism and the jellium model, including dielectric screening for the electron-electron interaction. The calculated redshift of the plasma frequency as the dielectric constant (ε) of the matrix increases is in good agreement with the available experimental data for both potassium and silver clusters. In the case of potassium, the shifts induced by rare-gas matrices are predicted. A tendency to saturation in the polarizability and surface plasmon resonance when ε increases is obtained and is due to the screening of the Coulomb interaction by the dielectric surrounding the cluster. We conclude that the basic effect of the dielectric matrix comes from the direct screening of the electron-electron interaction and not from the modification of the cluster ground state.