  Nano-plasmas produced, e.g. in clusters after short-pulse laser irradiation,
can show collective excitations as derived from the time evolution of
fluctuations in thermodynamic equilibrium. Molecular dynamical simulations are
performed for various cluster sizes. New data are obtained for the minimum
value of the stationary cluster charge. The bi-local auto-correlation function
gives the spatial structure of the eigenmodes, for which energy eigenvalues are
obtained. Varying the cluster size, starting from a few-particles cluster, the
emergence of macroscopic properties like collective excitations is shown.
