Model for mixture pair correlation functions: Prediction of chemical potential at infinite dilution

An approximation to the mixture pair correlation functions for spherically symmetric molecules is suggested. This approximation predicts the unlike pair correlation function in Lorentz-Berthelot mixtures by shifting the like pair correlation function by a distance equal to the difference in size between the large small molecules. Comparison to Lennard-Jones simulation data shows that this simple approximation predicts the behavior of the pair correlation function better than the common simple models, especially in the oscillating region beyond the first peak. The new pair correlation function approximation is then combined with statistical mechanical relationships to derive an accurate expression for the chemical potential at infinite dilution.