The role of quantal fluctuations in the optical response of small metal clusters

We present an ab initio calculation of the line shape of the photoabsorption spectrum of Na8 and Na+9 clusters at zero temperature, including the polarization effect driven by the electron-plasmon coupling, together with the electron-phonon coupling. The electron-plasmon coupling is found to yield a significant lowering of the energy centroid of the plasmons, whereas the main effect the electron-phonon coupling has is to smooth the spectrum. © 2005 IOP Publishing Ltd.