Critical Solution Behavior in a Binary Mixture of Gaussian Molecules. II

The critical solution properties of a model mixture have been examined. The system is composed of two gases (A and B) such that there are no AA or BB molecular interactions. The AB interaction is repulsive, with a negative Gaussian Mayer f function. The Mayer series for the free energy has been calculated through tenth power of the density (11-point graphs). By methods of Padé approximants nonclassical critical singularities have been found in the second composition derivative of the free energy (related to composition fluctuations), fourth composition derivative of the free energy, and the compressibility. An infinity in cp and a cusp in cυ are inferred. Thermodynamic questions discussed are the relations among the properties with pressure, density, or temperature as the independent variable; and the scaling laws. The critical fluctuations are also examined from the point of view of correlation functions.