A non-additive repulsive contribution in an equation of state: The development for homonuclear square well chains equation of state validated against Monte Carlo simulation

Abstract

This work consists of the adaptation of a non-additive hard sphere theory inspired by Malakhov and Volkov [Polym. Sci., Ser. A 49(6), 745-756 (2007)] to a square-well chain. Using the thermodynamic perturbation theory, an additional term is proposed that describes the effect of perturbing the chain of square well spheres by a non-additive parameter. In order to validate this development, NPT Monte Carlo simulations of thermodynamic and structural properties of the non-additive square well for a pure chain and a binary mixture of chains are performed. Good agreements are observed between the compressibility factors originating from the theory and those from molecular simulations.

Predicting the phase behavior of hydrogen in NaCl brines by molecular simulation for geological applications

“…This observation suggests that hydrogen solubility is rather driven by repulsion forces and consequently by volume effects. This assumption is corroborated by the recent work of Trinh et al (2016b) which exhibits a relationship between hydrogen solubility and free volume in various organic oxygenated solvents, showing thus that hydrogen solubility is more dependent on the available free space in the bulk than on the nature of the solvent. According to Trinh et al, since hydrogen has no kernel electron, its electronic cloud becomes highly deformable.…”

Modeling of mixed-solvent electrolyte systems

“…In some cases, additional binary interaction parameters had to be adjusted. For this, since the ions are considered to have negligible dispersive interactions, the algebraic average of the hard-sphere diameters was corrected using the approach proposed by Trinh et al [120], with an addition adjustable parameter ' o . The alcohol-water-salt systems was subsequently modeled fairly accurately in a fully predictive way (without any parameter adjustment between alcohol and ions).…”

“…@ are also incorporated along with these terms as proposed by Inchekel et al [73]. We will also use in this paper the correction for non-additivity of the hard sphere diameters (NAHS standing for Non-Additive Hard Sphere) that was proposed by Trinh et al [119,120]. The representative equation is given in eqn.…”

“…The additional term proposed by Trinh et al [120] is based on the observation that the usual combining rule that is used on the diameters should be corrected with a new parameter, which is called ' o :…”

“…Since the ions have no dispersive energy, it is impossible to use a v o for this purpose. This is why the non-additive diameter contribution developed by Trinh and coworkers [120] was used. This correction describes the fact that the cross-diameter is different from the arithmetic average of the two pure component diameters.…”