  We discuss some single particle properties of $^{16}$O and $^{40}$Ca using
correlated basis function theory and Fermi hypernetted chain equations with
central and tensor correlations. In particular, we concentrate on one body
density matrix, momentum distribution, natural orbits and quasi hole states.
The correlations are variationally generated by a realistic hamiltonian
containing the Argonne $v'_{8}$ two-nucleon and Urbana IX three-nucleon
interactions. The correlated momentum distributions show the well known
enhancement at large momenta, with a relative importance of the different
correlations (Jastrow and tensor) similar to that in nuclear matter. The
natural orbits and their occupation numbers are obtained by diagonalization of
the density matrix. The correlated first natural orbits occupations are
depleted by more than 10%, whereas the first following ones are occupied by a
few percent. The spectroscopic factors of the valence states are lowered by
$\sim 8-12%$ with respect to unity by central and tensor correlations,
confirming that short range correlations alone are not able to explain the
values extracted from $(e,e'p)$ experiments.
