  The dynamics of three coupled bosonic wells (trimer) containing $N$ bosons is
investigated within a standard (mean-field) semiclassical picture based on the
coherent-state method. Various periodic solutions (configured as $\pi$-like,
dimerlike and vortex states) representing collective modes are obtained
analitically when the fixed points of trimer dynamics are identified on the
$N$=const submanifold in the phase space. Hyperbolic, maximum and minimum
points are recognized in the fixed-point set by studying the Hessian signature
of the trimer Hamiltonian.
  The system dynamics in the neighbourhood of periodic orbits (associated to
fixed points) is studied via numeric integration of trimer motion equations
thus revealing a diffused chaotic behavior (not excluding the presence of
regular orbits), macroscopic effects of population-inversion and self-trapping.
In particular, the behavior of orbits with initial conditions close to the
dimerlike periodic orbits shows how the self-trapping effect of dimerlike
integrable subregimes is destroyed by the presence of chaos.
