  Some properties of small and medium sodium clusters are described within the
RPA approach using a projected spherical single particle basis. The oscillator
strengths calculated with a Schiff-like dipole transition operator and folded
with Lorentzian functions are used to calculate the photoabsorbtion cross
section spectra. The results are further employed to establish the dependence
of the plasmon frequency on the number of cluster components. Static electric
polarizabilities of the clusters excited in a RPA dipole state are also
calculated.
  Comparison of our results with the corresponding experimental data show an
overall good agreement.
