The liquid-vapour coexistence of charged hard spheres

We determine the liquid-vapour coexistence curve of the restricted primitive model of electrolytes by means of Monte Carlo simulations performed in the Gibbs ensemble and in a hyperspherical geometry. It is found that the Stillinger-Lovett condition is satisfied in the liquid phase but not in the vapour phase. This means that the latter could be dielectric. Whether this unexpected result is due to finite-size effects or not remains an open question.