Analysis of the velocity autocorrelation function of water

The centre-of-mass velocity autocorrelation function of liquid water under room conditions is examined through a mode-coupling approach developed to study monatomic liquids. The wavevector-dependent current correlations relevant to the theory are evaluated by computer simulations using a recently developed interaction potential, which accounts for the polarizability of the molecule. The theory is found to reproduce all the relevant dynamical features of water. Moreover, the analysis in terms of longitudinal and transverse contributions clarifies the origin of some peculiarities in the dynamics of this single-molecule correlation. A discussion of the corresponding spectra is also given.