This project aims to enhance the engineering modeling of hydrogen bonding, or association, by blending ab initio quantum calculations, fundamental molecular level findings from experimental techniques, and thermodynamic models. Because of the ubiquity of hydrogen bonding, applications for an improved association model are extensive, ranging from drug design to plastics manufacturing. Therefore, a substantial amount of work has been aimed at improving traditional thermodynamic tools, which often fail to capture the behavior of associating systems accurately. To guide models, spectroscopic techniques have been leveraged to gain insight into the interactions between molecules in the liquid phase, but interpretation is difficult. Moreover, with the advancement of computational chemistry technology, molecular dynamics (MD) and quantum mechanical (QM) calculations have also been utilized to understand the characteristics of hydrogen bonded clusters. However, few studies have combined all 3 techniques (the thermodynamic model, spectroscopy and ab initio calculations) in a rigorous way. To this end, an activity coefficient model for association is developed using Wertheim’s perturbation theory and its capabilities and limitations are explored with parameters from literature. Furthermore, a sequential MD and QM protocol is designed which facilitates the interpretation of the hydroxyl vibration in infrared spectroscopy and a method is developed to quantify the entire band. Finally, the methods are used to calculate the value of the association constant for an alcohol + alkane system.
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