(252d) Fluid-Phase Properties Using Direct Calculation of Cluster Integrals

The Mayer-sampling method is a recently introduced technique for calculation of cluster integrals using methods related to those applied for the calculation of free energies. These cluster integrals appear in expressions relating the virial coefficients to the intermolecular potential, and in integral-equation theories for condensed phases. In this work we demonstrate how the Mayer-sampling method can be used to calculate high-order virial coefficients for complex molecules and their mixtures. The calculation can be aided by relations derived from integral-equation techniques. The coefficients so obtained can be effective in describing the fluid to densities at and beyond the critical point, and thus provides a means for estimating the location of the critical point of both pure substances and mixtures. We discuss applications to a variety of molecules, including alkanes up to dodecane, alcohols, water, and others.