  Spherical confinement can alter the properties of a dipolar fluid in several
different ways. In an atomistic molecular dynamics simulation study of two
different dipolar liquids (SPC/E water and a model Stockmayer fluid) confined
to nanocavities of different radii ranging from Rc=1nm to 4nm, we find that the
Kirkwood correlation factor remains surprisingly small in water, but not so in
model Stockmayer liquid. This gives rise to an anomalous ultrafast relaxation
of the total dipole moment time correlation function (DMTCF). The static
dielectric constant of water under nanoconfinement (computed by employing
Clausius-Mossotti equation, the only exact relation) exhibits a strong
dependence on the size of the nanocavity with a remarkably slow convergence to
the bulk value. Interestingly, the value of the volume becomes ambiguous in
this nanoworld. It is determined by the liquid-surface interaction potential
and is to be treated with care because of the sensitivity of the
Clausius-Mossotti equation to the volume of the nanosphere. We discover that
the DMTCF for confined water exhibit a bimodal 1/f noise power spectrum. We
also comment on the applicability of certain theoretical formalisms that become
dubious in the nanoworld.
