The decomposed density of states for the entire water film on different metals as obtained by the DoSPT program are shown in Figure . Since the studied water films have two interfaces, one with the metal and another with the vacuum, the changes with respect to bulk DoS occur on both sides. The translational bulk frequencies correspond to the skewed Gaussian band that peaks at around 50 cm -1 , while the rotational motions lead to the broad Gaussian type band centered at around 500 cm -1 . The rotational contributions to the DoS on the metal surfaces are rather independent of the presence of the metal substrate and are nearly indistinguishable from those of bulk water. Because the high-frequency stretching and bending modes are also close to their bulk liquid properties (shown in Figure ), here we focus on the translational modes only.