Memory functions and the calculation of dynamical properties of atomic liquids

The memory function approach is discussed with respect to the representation of computer generated time correlation functions. Single-particle and collective properties of the Lennard-Jones fluid are considered, and the usefulness of directly evaluated memory functions and model memory functions is discussed. The scatterirng functions analysis is restricted to the medium and small wave vector range in order to demonstrate the approximate hydrodynamic behaviour of these functions, that can be exploited to determine transport coefficients. Furthermore, the method of determining thermal transport coefficients via a single Gaussian memory function is presented in direct comparison with molecular dynamics results. Experimental aspects are considered. Finally a limited comparison of results for the Lennard-Jones and the hard sphere fluids is given.