  We study the dependence of the excitation frequency of water along an
isochore and an isotherm crossing the region of density anomaly. We have shown
that the frequency of the longitudinal excitations demonstrated anomalous
dependence on temperature along the isochore. At the same time the dependence
for both longitudinal and transverse excitation frequencies on density along
the isotherm are very modest or even negligible in rather wide range of
densities. This kind of behavior also seems anomalous in comparison with the
ordinary liquids.
