Understanding and Quantifying the Physico-chemical Behavior of Complex Systems

Many physico-chemical processes such as nucleation events in phase transitions, chemical reactions, conformational changes of biomolecules, and protein folding are activated processes that involve rare transitions between stable or metastable states in the free energy surface. Understanding the underlyingmechanism and computing the rates associated with such processes is a central to many applications. For instance, the familiar process of nucleation of ice from supercooled water is encountered in several scientific and technologically relevant processes. The formation of ice microcrystals in clouds via nucleation is a phenomenon that has a large impact in terms of governing global climatic changes. The key to the survival of Antarctic fish and certain species of beetles through harsh winters is their ability to inhibit nucleation of intracellular ice with the aid of antifreeze proteins. At the other end of the spectrum, certain protein assemblies called ice-nucleation agents are believed to be responsible for catalyzing ice nucleation, a phenomenon, which is exploited by certain bacteria to derive nutrients from their host plants. Controlling the formation and propagation of intracellular ice is finding importance in cryopreservation of natural and biosynthetic tissues. Similarly, one can cite many technologically relevant self-assembly and transport processes in the context of fabrication of advanced materials for specific applications in drug delivery, biosensing, and chemical catalysis. A unifying feature among various activated events is that they can be understood in terms of transitions between a series of stable (global minimum)