  The Faddeev technique is employed to study the influence of both
particle-particle and particle-hole phonons on the one-hole spectral function
of 16O. The formalism includes the effects of nuclear fragmentation and
accounts for collective excitations at a random phase approximation (RPA)
level. The latter are subsequently summed to all orders by the Faddeev
equations to obtain the nucleon self-energy. The results indicate that the
characteristics of hole fragmentation are related to the low-lying states of
16O and an improvement of the description of this spectrum is required to
understand the details of the experimental strength distribution. A first
calculation to improve on this includes the mixing of two-phonon configuration
with particle-hole ones. It is seen that this allows to understand the
formation of excited states which cannot be described by the RPA approach.
