Computational exploration of water structure and dynamics at heterogeneous interfaces

The goal of this thesis is to completely understand the dynamical behavior of
water at different heterogeneous interfaces through statistical mechanics and
computational methods. The molecular processes described here has been focused
for past few decades, since the advent of experimental techniques to probe
interfacial water molecules. A central theme throughout the thesis is to have
quantitative understanding of water dynamics and structural interactions at the
microscopic level. This work has immense importance in the field of analytical
chemistry, surface science and biophysics.
We first describe the model for the intercalation process of a probe molecule in
the chromatographic system. This study is relevant for industrial HPLC techniques,
however complete microscopic level understanding of this process is still not
completely understood. The effect of various solvent concentrations and phase
thickness on the process of intercalation of acridine orange (probe) has been studied.
An extension to this work is the thermodynamic model for intercalation
of organic compounds based on experimentally known partition coefficient data.
Another interesting process is related with the vibrational spectroscopic feature of
water at hydroxylated silica surface. A lot of experimental studies has been
done to probe vibrational feature of water at solid interface and relate it to H-bonding
structure at these interfaces. Most of these results focused on the vibrational
feature in the streching frequency regime of water but we focused on the vibrational
bending mode of water close to the bare hydroxylated silica surface. This study
demonstrate the importance of higher order multipoles to capture the precise
spectroscopic description. Both the above studies are discuss in great detail in chapter IV.
Other interesting system we studied is the allosteric proteins, which mainly includes
Dimeric Scapharca Hemoglobin and Tetrameric human hemoglobin. This study mainly focus
on the role of water molecules close to protein surface and disentangle the coupled
dynamics of ligand and water molecules at the interface. Finally, we will describe
the quaternary structural transition T to R in tetrameric human hemoglobin. This
work is described in chapter V of this thesis.