R -crossing method applied to fluids interacting through variable range potentials

Abstract

The R-crossing method of thermodynamic geometry is applied to reproduce the coexistence curves of fluid systems described by hard-core Yukawa and hard-core Mye-Type interactions whose range can be varied. Connection between the range of the potential and the validity of the method is studied. Even when scaling relations suggest a dependence on the range, we found explicitly the quantitative dependence for two varying range potentials. Using the saturation pressures, it is possible to assign a percentage P(λ) of measuring how far we can go below the critical point when reproducing the coexistence curve. It is found that there is a close relation between the range of the potential and P(λ). Such relation assures that the larger the range of the potential, the deeper we can go below the critical point. Our results, together with the known low |R| limit, represent two independent criteria to restrict the applicability of the R-crossing method. Namely, at what extent we can accurately reproduce the coexistence curve when we know the range of the intermolecular potential of the thermodynamic system involved.