We present the latest developments in thermodynamic modeling using the SAFT-γ Mie group-contribution equation of state. The group database is updated, featuring now 58 groups; this expanded database incorporates new parameters for interactions between both like and unlike groups. This provides the capability to treat mixtures including alcohols, ethers, ketones, carboxylic acids, and acetates, amines, aromatic and cyclic compounds, electrolytes, inorganic acids, and some common solvents, such as water and acetone. A discussion is provided relating to the assignment of the groups, including some secondary groups that are introduced for multifunctional molecules to capture the influence of molecular polarization effects on the thermodynamic properties. Performance of the SAFT-γ Mie approach is illustrated for a wide variety of systems, highlighting its use in describing solid−liquid as well as vapor−liquid and liquid−liquid equilibria.
The link between the static dielectric constant and the microscopic intermolecular interactions is the Kirkwood g1 factor, which depends on the orientational structure of the fluid. Over the years, there have been several attempts to provide an accurate description of the orientational structure of dipolar fluids using molecular theories. However, these approaches were either limited to mean-field approximations for the pair correlation function or, more recently, limited to adjusting the orientational dependence to simulation data. Here, we derive a theory for the dielectric constant of dipolar hard-sphere fluids using the augmented modified mean-field approximation. Qualitative agreement is achieved throughout all relevant thermodynamic states, as demonstrated by a comparison with simulation data from the literature. Excellent quantitative agreement can be obtained using a single empirical scaling factor, the physical origin of which is analyzed and accounted for. In order to predict the dielectric constant of the Stockmayer fluid (Lennard-Jones plus dipole potential), we use an adjusted version of the expression for the dipolar hard-sphere fluid. Comparing theoretical predictions with newly generated simulation data, we show that it is possible to obtain excellent agreement with simulation by performing the calculations at a corresponding state using the same scaling factor. Finally, we compare the theoretical orientational structure of the Stockmayer fluid with that obtained from simulations. The simulated structure is calculated following a post-processing methodology that we introduce by deriving an original expression that relates the proposed theory to the histogram of relative dipole angles.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.