Low frequency Raman spectra of liquid water, a molecular dynamics simulation

A molecular dynamics simulation of the very low frequency depolarized Raman spectrum of water is presented and compared with the experimental data. The molecular trajectories of 108 water molecules, interacting via the TIP4P effective potential, were recorded during 200 ps at five thermodynamic states including the supercooled liquid. The Raman spectrum is calculated truncating the polarizability expansion at the first order dipole-induced-dipole term. The agreement of the simulated spectra with the experiments as far as lineshape and intensity is concerned, allows to ascribe the light scattering excess around the incident frequency to collision induced contributions, namely the dipole-induced-dipole spectrum.