Fields of Study
Areas of Interest
My research interests in theoretical physical chemistry are primarily concerned with the structure, phases and dynamics of complex liquid and biological systems. Although the static and transport properties of simple liquid systems are fairly well understood, much less is known about complex liquid systems of great importance in biochemistry and materials chemistry. The unifying theme of our research is the judicious application of analytic theory, computer simulation and computational chemistry to elucidate the molecular foundations of the structure and macroscopic behavior of complex chemical systems. In addition to previous work on the statistical mechanics of time-dependent properties of equilibrium and steady-state fluids, there are currently several projects of particular interest.
The first project focuses mainly on the role of charge and aquation state in the determination of macromolecular structure in biological systems. There has been very little theoretical work on how the conformation of an isolated macromolecule depends on the number of excess charges bound to it, in spite of the fact that many protein and polypeptide molecules contain ions and are present in a variety of charge states at biological pH conditions. We are working on new molecular dynamics and Monte-Carlo simulation methods which are designed to reproduce the correct statics and dynamics of charged polypeptides and other molecules in which proton transfer is important. The goal of the work is to probe how the transitions between folded and extended conformers depend on temperature, aqueous solvation and charge state of the molecule.
Another area of interest is the nature of dynamics of systems with a rough energy landscape. Non-exponential relaxation, experimentally observed in the dynamics of dense glassy fluids and proteins, is a common feature of systems possessing a complex potential energy surface. From a kinetic perspective, such systems typically show significant departures from Arrhenius behavior. It is therefore interesting to try to understand which generic features of the potential energy surface lead to such complicated behavior. In particular, it is appealing to try to establish connections between gross topological features of the potential energy surface, such as funnels, and important dynamical events leading to structural relaxation. We have been working at establishing rigorous theoretical methods to elucidate the complex nature of dynamics in systems with rough energy landscape. In particular, recent work has focused on utilizing mode-coupling theory to provide a microscopic framework for examining dynamic heterogeneity in supercooled systems. Concurrently, we are conducting computer simulation studies to formulate good measures of various aspects of the dynamics.