NETWORK ANALYSIS ALGORITHMS AND APPLICATIONS TO UNDERSTAND AQUEOUS SOLUTIONS AND THEIR INTERFACES
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Computational simulations have been widely used in a variety of disciplines including physics, chemistry, materials science and biology. Intermolecular Network Theory (INT) provides a generalized multiscale analysis framework that can be utilized to investigate the associated structural and dynamic properties of the intermolecular interactions of chemical systems across different length scales and time scales. New analysis techniques within INT are described and then applied to understand the structures and dynamics of water hydrogen bond network in liquid water, its aqueous solutions and interfaces. The transitions between patterns of hydrogen bonding are shown to reveal underlying molecular motions, as demonstrated for water reorientation. This work describes the detailed network analyses of water hydrogen bond dynamics about non-polar alkanes and under hydrophobic confinement. In the former, no structure enhancement is observed for water in the first hydration shell of alkanes; while a significant dynamic retardant effect is observed in terms of the water reorientation motion. In the latter, both the structural organization of the hydrogen bond network and its dynamics are massively perturbed. Using INT in combination with second-order Møller-Plesset perturbation theory, it reveals that the effect of hydrophobic confinement is predominantly (~75%) due to geometric restriction, however the competition of intermolecular forces, specifically the weakly attractive hydrophobic interaction with the confining surface, has a significant (~25%) impact. In addition, the interfacial structures and dynamics of water at the bi-phasic water/vapor and water/organic interfaces have also been investigated using INT, wherein it is demonstrated that capillary wave fronts at the interface are both structurally and dynamically heterogeneous. This interfacial heterogeneity has been correlated with the surface-sensitive vibrational sum frequency generation experiments at a soft charged aqueous interface.