Towards the development of theoretically correct liquid activity coefficient models

Dielectric continuum methods for quantum chemistry

“…As compared to these methods, an even blacker‐box approach that is sometimes encountered in chemistry applications (but more often in the chemical engineering literature) is “COSMO‐RS,” 197,376–380 a model developed by Klamt and coworkers based on COSMO electrostatics (Section 2.4) but designed for “real solvents.” As its basic ingredient, COSMO‐RS uses a coarse‐grained version of the COSMO surface charge density σ ( s ), averaged over segments of the cavity surface to define a “ σ ‐profile.” Solution‐phase activities are then parameterized in terms of the σ ‐profile, and this constitutes a QM‐based alternative to other parameterized activity coefficient models that are widely used in engineering thermodynamics 381–384 . However, modern versions of COSMO‐RS are available only in the proprietary cosmotherm software, 378 and attempts by other groups to implement (or sometimes even to use) COSMO‐RS and related models outside of the cosmotherm program have been met with harsh criticism from Klamt 385–414 . The tenor of those discussions strongly suggests that insufficient details are available in the literature that would allow others to implement COSMO‐RS 306,387,390,393,396,405,408,411,414,415 .…”

Symmetrization of excess Gibbs free energy: A simple model for binary liquid mixtures

“…Following the same conventions, the total number of pairs (i, j) can also be written as N i N ji , and the pair conservation condition will be N i N ji = N j N ij. According to Lin et al [10] in order to fulfill the pair conservation rule, the coordination number, or the effective contact in our case, must be expressed as:…”

“…In order to express this condition, consider the total number of pairs (j, i), as the product N j N ij , where N ij is the number of molecules i surrounding the j molecule, and N j is the number of molecules j in the liquid. Following the same conventions, the total number of pairs (i, j) can also be written as N i N ji , and the pair conservation condition will be N i N ji = N j N ij (see Lin et al [10]). …”

“…Recently, Lin et al [10] have shown that the Wohl model of the activity coefficient expansion fulfills the pair conservation condition (see Appendix A). This activity coefficient can be obtained from the equation:…”

Improved Prediction of Phase Behaviors of Ionic Liquid Solutions with the Consideration of Directional Hydrogen Bonding Interactions

“…For example, COSMO-based models like COSMO-RS and COSMO-SAC are the outstanding examples of such models. These models have a sound theoretical basis and have been shown to provide reasonably accurate predictions for a wide varieties of fluid mixtures, including organic fluids, − pharmaceuticals, − gas molecules, , supercritical fluids, , electrolytes, − and ionic liquids (ILs). − …”