On the response function of simple metal clusters

We analyse the response function of simple metal clusters considering several theoretical approaches and exploring a large class of momenta and energies. The study is performed on a wide range of cluster sizes to explore the relative weight of the various dominant contributions to the response. We work with Sodium clusters in jellium approximation. The comparison between the various theoretical approaches shows altogether a remarkable consistency. The simple Boson approximation to the response function is furthermore shown to perform remarkably well in spite of its simplicity.