Modification of a kinetic model of the generalized Enskog equation

It is pointed out that a previously proposed kinetic model of the generalized Enskog equation does not describe properly the hydrodynamic spectrum of density fluctuations because of the neglect of the momentum state corresponding to the longitudinal stress tensor in the representation of the memory function. It is shown that inclusion of this state leads to a kinetic model which gives results in agreement with light-scattering data.