A molecular dynamics study of a liquid-liquid interface: structure and dynamics

The liquid-liquid (L/L) interface between two partially miscible model Lennard-Jones fluids is investigated in the temperature range 100 K less than or equal to T less than or equal to 138 K using molecular dynamics computer simulations. The equilibrium compositions in the two phases agree reasonably well with recent results from DFT theory. The structure of the L/L interface is characterized in terms of partial density profiles of the two components and the interfacial tensions are computed for all temperatures using the virial method. The self-diffusion coefficients are determined as a function of temperature and distance from the interface and are compared to the ones of the pure liquids under identical conditions. A slight anisotropy is found in the interfacial system. It is restricted to the regions of strong variations of the partial density profiles and is due to an enhancement of the tangential components of the self-diffusion coefficients compared to the components Ds N normal to the interface. (C) 2004 Elsevier B.V. All rights reserved.