Influence of static electric field on the vapour–liquid coexistence of dipolar soft-sphere fluids

Abstract

The influence of a static homogeneous electric field on the vapour–liquid equilibrium of dipolar soft-sphere fluids has been studied by the Gubbins–Pople–Stell perturbation theory. The thermodynamic properties of the fluid as functions of the field strength were derived from the Helmholtz energy containing the field-dependent relative permittivity. The dielectric saturation was studied by a perturbation theoretical treatment of the Kirk-wood equation. Our calculations can yield a weak negative saturation. It was found that the critical quantities increase, while the temperature range of the phase coexistence narrows with the field strength. A comparison between our electrostriction results and simulation data shows reasonable agreement at low field strengths.