EFFECTIVE EIGENMODE DESCRIPTION OF DYNAMIC PROCESSES IN DENSE CLASSICAL FLUIDS AND FLUID MIXTURES

We review the description of dynamical processes in dense classical fluids by means of effective eigenmodes. These eigenmodes effectively represent the (microscopic) dynamical behaviour of the fluid on the molecular scale as far as time correlation functions or dynamic structure factors are concerned, that are observed in light, neutron or computer experiments. These effective eigenmodes can be determined either theoretically from hydrodynamic or kinetic theory or experimentally from an exponential or Lorentzian fit to observed correlation functions. We also consider the relevance of these modes for fluid mixtures and colloidal suspensions. © 1990 Società Italiana di Fisica.