The activity coefficient of high density systems with hard-sphere interactions: the application of the IGCMC method

Abstract

The inverse grand-canonical Monte Carlo (IGCMC) technique is used to calculate the activity coefficients of the following hard-sphere systems: one-component fluid, binary mixture and solvent primitive model (SPM) electrolyte. The calculations for a one-component fluid are performed at different densities. The components of a binary mixture differ in diameters (300 and 500 pm) with the results being presented for different density and composition of a mixture. For the SPM model, simulations are performed for a 1:1 electrolyte at different electrolyte concentrations at the packing fraction equal to 0.3. Ions and solvent molecules of the same or different sizes are considered. The results are compared with those reported by Adams (one-component fluid), with those calculated using the Ebeling and Scherwinski equation (one-component fluid and binary mixture) and with the predictions from the symmetric Poisson–Boltzmann theory and the mean spherical approximation (SPM electrolyte).

Keywords:

• activity coefficient
• inverse grand-canonical Monte Carlo method
• hard-sphere interactions
• solvent primitive model electrolyte
• GCMC simulation

Acknowledgements

The authors are very grateful to Professors C.W. Outhwaite and L.B. Bhuiyan for their comments and suggestions and for making available their SPB program. Financial support from Adam Mickiewicz University, Faculty of Chemistry, is appreciated.