  We present an investigation of vibrational features in water clusters
performed by means of our recently established divide-and-conquer semiclassical
approach [M. Ceotto, G. Di Liberto, and R. Conte, Phys. Rev. Lett. 119, 010401
(2017)]. This technique allows us to simulate quantum vibrational spectra of
high-dimensional systems starting from full-dimensional classical trajectories
and projection of the semiclassical propagator onto a set of lower dimensional
subspaces. The potential energy surface employed is a many-body representation
up to three-body terms, in which monomers and two-body interactions are
described by the high level Wang-Huang-Braams-Bowman (WHBB) water potential,
while, for three-body interactions, calculations adopt a fast permutationally
invariant ab initio surface at the same level of theory of the WHBB 3-body
potential. Applications range from the water dimer up to the water decamer, a
system made of 84 vibrational degrees of freedom. Results are generally in
agreement with previous variational estimates in the literature. This is
particularly true for the bending and the high-frequency stretching motions,
while estimates of modes strongly influenced by hydrogen bonding are red
shifted, in a few instances even substantially, as a consequence of the
dynamical and global picture provided by the semiclassical approach.
