Effect of the range of interactions on the properties of fluids. Phase equilibria in pure carbon dioxide, acetone, methanol, and water

The effect of the long-range Coulombic interactions on the vapor-liquid equilibria properties of polar and associating fluids has been investigated, by considering typical representatives of these classes of fluids, namely, carbon dioxide, acetone, methanol, and water, defined by realistic intermolecular pair potential models. Using the same decomposition of realistic potential models into a short-range part and a residual part as in previous papers Nezbeda, I. Mol. Phys. 2000, 98, 1505-1520 Lısal, M. Mol. Phys. 2001, 99, 1751-1764, we carried out Gibbs ensemble simulations on both the full and shortrange models to determine the thermodynamic properties of the considered compounds along the vaporliquid coexistence curve. In addition, we also considered methanol in two homogeneous phases, liquid and supercritical, to determine its structure and thermodynamic properties. We have found that the long-range interactions affect all considered properties only marginally and that the short-range system provides a reasonably accurate and reliable zeroth-order approximation. A simple theoretical analysis has also been made to explain and estimate the effect of the long-range interactions on the thermodynamic properties both in the homogeneous phase and at phase equilibrium