Liquids are generally disordered systems, but in terms of disorder we distinguish between two types of liquids: simple and complex. A typical example of a simple liquid is liquid carbon tetrachloride, while complex liquids can form molecular assemblies, such as those in hydrogen-bonded systems like water and alcohols. We analyze the time dependent atom-atom correlation functions in these systems in order to find characteristic features due to the molecular association. Important dynamical quantities of interest are the van Hove functions, the intermediate scattering functions and the dynamical structure factors as calculated from the Molecular Dynamics simulations. The most important difference is the existence of kinetic processes due to clustering, which are prominently found in the small k part of atom-atom dynamical structure factors  S(k,w) of complex disorder liquids, and are totally absent from the simple disorder liquids.

Contact: Claude Millot