Equilibrium properties of penetrable soft spheres

Abstract

Using the Weeks-Chandler-Andersen separation scheme, we explored equilibrium properties of fully penetrable soft spheres with an attractive tail. When the radial distribution function of the reference system is computed by means of the integral equation theory using the hyper-netted-chain closure, this separation scheme predicts pressure-density isotherms, vapour-liquid phase coexistence, and surface tension in good agreement with the results from Monte Carlo simulations even though the attractive portion of the interparticle potential has a significant effect on the radial distribution function. Despite its simplicity, the model potential we studied, with a certain parameter value, exhibits a non-monotonic temperature dependence of the liquid phase density over a wide range of pressure.

GRAPHICAL ABSTRACT

Keywords:

• Penetrable soft spheres
• thermodynamic perturbation theory
• Weeks-Chandler-Andersen separation scheme
• hyper-netted-chain closure
• surface tension

Acknowledgments

Computations reported here were made possible by a resource grant from the Ohio Supercomputer Center [30]. We are grateful for helpful comments from Professor Lisa M. Hall on the integral equation theory during the early stage of this work. A preliminary GEMC simulation carried out by Nicholas T. Liesen on soft spheres provided a motivation for this work.

Disclosure statement

No potential conflict of interest was reported by the author(s).