  A variational wave function constructed with correlated Hyperspherical
Harmonic functions is used to describe the Helium trimer. This system is known
to have a deep bound state. In addition, different potential models predict the
existence of a shallow excited state that has been identified as an Efimov
state. Using the Rayleigh-Ritz variational principle the energies and wave
functions of both bound states have been obtained by solving a generalized
eigenvalue problem. The introduction of a suitable correlation factor reduces
considerably the dimension of the basis needed to accurately describe the
structure of the system. The most recent helium-helium interactions have been
investigated.
