Noura Dawass

162 S UMMARY the following shapes of the subvolume: sphere, cube, and cubiods and spheroids with different aspect ratios. It turns out that in the thermodynamic limit, KBIs are independent of the shape of the used subvolume. In chapter 3, finite–size effects related to computing KBIs from molecular simulations were investigated. Finite–size effects originating from the size of the system and the size of the used subvolumes were studied using an analytic RDF. From KBIs computed for different sizes of the subvolume, we found that the size of the subvolume should not exceed the size of the simulation box. In this chapter, finite–size effects related to computing RDFs from closed systems were also studied for a Weeks-Chandler-Andersen (WCA) fluid. RDFs computed from Molecular Dynamics (MD) simulations of closed and finite systems were corrected to estimate RDFs of open systems, which are required by the KB the- ory. The performance of three correction methods was assessed: (1) a 1/ N cor- relation [74] , (2) a correction by Ganguly and van der Vegt [113] , and (3) an ex- pression by Cortes-Huerto and co–workers [83] . The correction by Ganguly and van der Vegt was found to provide the most accurate KBIs. KBIs in the thermo- dynamic limit were obtained from the linear part of the scaling of KBIs of small subvolumes ( G V αβ ) with the inverse size of the system 1/ L . Identifying a linear regime was not straightforward, and some guidelines were provided. In chapter 4, KBIs of Lennard–Jones (LJ) and WCA fluids at various densities were computed. To obtain KBIs in the thermodynamic limit from RDFs com- puted using MD simulations of finite systems, three extrapolation methods were considered. All extrapolation methods resulted in similar estimations of KBIs, however, the scaling of LG V αβ with L was found the easiest to use. Additionally, surface effects of KBIs of LJ and WCA fluids were quantified. The results demon- strated that for LJ and WCA systems, surface terms can be of the same order of magnitude of KBIs. In chapter 5, KBIs of mixtures of urea and choline–chloride (ChCl) were com- puted using MD simulations. The system was studied at T = 343.15 K, atmo- spheric pressure, and molar ratios of ChCl to urea ranging from 2:1 to 1:5. RDFs were corrected using the Ganguly and van der Vegt correction, and the scaling of LG V αβ with L was used to obtain KBIs in the thermodynamic limit. KBIs were used to examine the affinity between the various components at different molar ratios. From the KBIs, thermodynamic factors and partial molar volumes were directly computed. Also, from MD simulations, a number of transport proper- ties were studied including MS diffusivities, that are connected to Fick diffusion coefficients via the thermodynamic factors. It was shown that the KB theory is advantageous for simultaneously studying molecular interactions and comput- ing thermodynamic properties of salt solutions.