Calculating thermodynamic factors of ternary and multicomponent mixtures using the Permuted Widom test particle insertion method

Abstract

We present an approach to calculate thermodynamic factors for multicomponent liquid mixtures from molecular simulations by the Permuted Widom test particle insertion method. The thermodynamic factors relate experimentally obtained Fick diffusion coefficients and the Maxwell–Stefan diffusion coefficients computed from molecular simulations/theory. In our earlier work, we presented the Permuted Widom test particle insertion method (Balaji et al. in Mol Phys 2012) for calculating thermodynamic factors for binary systems from a single simulation. In this paper, we have extended this approach to ternary systems consisting of Lennard–Jones particles. The thermodynamic factors computed from the simulations and from numerically differentiating the activity coefficients obtained from the conventional Widom single test particle insertion method were compared. An excellent agreement was observed.