Role of effective atomic masses in memory function-based models for liquids: a simulation study of liquid water.

The theoretical description of the dynamics of liquids by the theory of Mori and Zwanzig is in practice mostly applied to simple liquids, where the molecules have no internal structure. Recently a second-order Mori-Zwanzig model for the incoherent intermediate scattering function has been employed in order to interpret quasielastic neutron scattering QENS experiments on water and aqueous solutions of nonpolar molecules. In this framework the time evolution of the single particle correlation function F q , t = exp iq R t −R 0 is described by