  The static response properties and the structural stability of silver
clusters in the size range $1\le n \le 23$ have been studied using a linear
combination of atomic Gaussian-type orbitals within the density functional
theory in the finite field approach. The Kohn-Sham equations have been solved
in conjuction with a generalized gradient approximation (GGA)
exchange-correlation functional. A proof that the finite basis set GGA
calculation holds the Hellmann-Feynman theorem is also included in the
Appendix. The calculated polarizabilities of silver clusters are compared with
the experimental measurements and the jellium model in the spillout
approximation. Despite the fact that the calculated polarizabilities are in
good agreement with both of them, we have found that the polarizability appears
to be strongly correlated to the cluster shape and the highest occupied-lowest
unoccupied molecular-orbital gap.
