Iwai et al. proposed a new model for activity coefficients in the previous work [Y. Iwai, Fluid Phase Equilib. 465 (2018) 24-33]. In this work, the number of interactions for Lennard-Jones fluids in liquid phase was calculated by molecular dynamics simulation to check the validity of the assumptions in the new model. The calculated results show that the number of interactions per molecule depends on partner molecules and concentrations, and the assumptions are reasonable. The new model was applied to correlate the activity coefficients for the real systems in which the activity coefficients exceptionally increase or decrease in the dilute regions. The vapor-liquid equilibria for hydrocarbon + alcohol systems were calculated by combining an equation of state with excess Gibbs free energy (G(E)) mixing rules. It is observed that the calculated results of vapor-liquid equilibria are improved by using the new model for G(E). (C) 2019 Elsevier B.V. All rights reserved.