Monte Carlo simulations of primitive models for ionic systems using the Wolf method

Abstract

Thermodynamic and structural properties of primitive models for electrolyte solutions and molten salts were studied using NVT and NPT Monte Carlo simulations. The Coulombic interactions were simulated using the Wolf method [D. Wolf, Phys. Rev. Lett. 68, 3315 (1992); D. Wolf, P. Keblinnski, S. R. Phillpot, and J. Eggebrecht, J. Chem. Phys. 110, 8254 (1999)]. Results for 1 : 1 and 2 : 1 charge ratio electroneutral systems are presented, using the restricted and non-restricted primitive models, as well as a soft PM pair potential for a monovalent salt [J.-P. Hansen and I. R. McDonald, Phys. Rev. A 11, 2111 (1975)] that has also been used to model 2 : 12 and 1 : 20 asymmetric colloidal systems, with size ratios 1 : 10 and 2 : 15, respectively [B. Hribar, Y. V. Kalyuzhnyi, and V. Vlachy, Molec. Phys. 87, 1317 (1996)]. We present the predictions obtained for these systems using the Wolf method. Our results are in very good agreement with simulation data obtained with the Ewald sum method as well as with integral-equation theories results. We discuss the relevance of the Wolf method in the context of variable-ranged potentials in molecular thermodynamic theories for complex fluids.

Acknowledgements

This work was supported under CONACYT grants 2002-C01-41678 and 2003-C03-42439/A-1. C. Avendaño acknowledges a PhD scholarship from CONACYT. The authors thank the anonymous referee of this article for very useful suggestions that helped us to improve the presentation of our results. We acknowledge Andrew Haslam (Imperial College of London, UK), who motivated us to start this research, together with Enrique González-Tovar and Iván Guerrero-García (Instituto de Física de la Universidad Autónoma de San Luis Potosí, México) and Hugh Docherty (Imperial College of London, UK) for interesting discussions.