  A structural transformation in water upon compression was recently observed
at the temperature $T=277$~K in the vicinity of the pressure $p \approx
2\;000$~Atm [R.M. Khusnutdinoff, A.V. Mokshin, J. Non-Cryst. Solids
\textbf{357}, 1677 (2011)]. It was found that the transformations are related
with the principal structural changes within the first two coordination shells
as well as the deformation of the hydrogen-bond network. In this work we study
in details the influence of these structural transformations on the vibrational
molecular dynamics of water by means of molecular dynamics simulations on the
basis of the model Amoeba potential ($T=290$~K, $p=1.0 \div 10\;000$~Atm). The
equation of state and the isothermal compressibility are found for the
considered ($p$,$T$)-range. The vibrational density of states extracted for
$THz$-frequency range manifests the two distinct modes, where the
high-frequency mode is independent on pressure whereas the low-frequency one
has the strong, non-monotonic pressure-dependence and exhibits a step-like
behavior at the pressure $p \approx 2000$~Atm. The extended analysis of the
local structural and vibrational properties discovers that there is a strong
correlation between the primary structural and vibrational aspects of the
liquid-liquid structural transformation related with the molecular
rearrangement within the range of the second coordination shell.
