Dissipative particle dynamics for interacting systems

We introduce a dissipative particle dynamics scheme for the dynamics of non ideal fluids. Given a free-energy density that determines the thermodynamic s of the system, we derive consistent conservative forces. The use of these effective, density dependent forces reduces the local structure as compare d to previously proposed models. This is an important feature in mesoscopic modeling, since it ensures a realistic length and time scale separation in coarse-grained models. We consider in detail the behavior of a van der Waa ls fluid and a binary mixture with a miscibility gap. We discuss the physic al implications of having a single length scale characterizing the interact ion range, in particular for the interfacial properties. (C) 2001 American Institute of Physics.