Absorption spectra of closed-shell Na_2, Na_3+, Na_4, Na_5+, Na_6, Na_7+, andNa_8 clusters are calculated using a recently implemented conserving linearresponse method. In the framework of a quasiparticle approach, we determineelectron-hole correlations in the presence of an external field. The calculatedresults are in excellent agreement with experimental spectra, and some possiblecluster geometries that occur in experiments are analyzed. The position and thebroadening of the resonances in the spectra arise from a consistent treatmentof the scattering and dephasing contributions in the linear responsecalculation. Comparison between the experimental and the theoretical resultsyields information about the cluster geometry, which is not accessibleexperimentally.
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