  This work is devoted to the elucidation the applicability of jellium model to
the description of alkali cluster properties on the basis of comparison the
jellium model results with those derived from experiment and within ab initio
theoretical framework. On the basis of the Hartree-Fock and local-density
approximation deformed jellium model we have calculated the binding energies
per atom, ionization potentials, deformation parameters and the optimized
values of the Wigner-Seitz radii for neutral and singly charged sodium clusters
with the number of atoms N <= 20. These characteristics are compared with the
results derived from the ab initio all-electron simulations of cluster
electronic and ionic structure based on the density functional theory as well
as on the post Hartree-Fock perturbation theory on many-electron correlation
interaction. The comparison performed demonstrates the great role of cluster
shape deformations in the formation cluster properties and the quite reasonable
level of applicability of the deformed jellium model.
