Professor Adam Willard, MIT.  Theoretical Chemistry Talk.  Part 1:  "Nanoscale Disorder Drives and the Dynamics of Excitons in Molecular Semiconductors."   Part II:  "What Can Interfacial Water Molecules Tell Us About Solute Structure?”

Part I: “Nanoscale Disorder Drives the Dynamics of Excitons in Molecular Semiconductors"

Many organic electronic materials are composed of soft condensed matter that is both electronically active and disordered on the nanoscale. The electronic properties of these materials can depend sensitively on the details of molecular morphology, reflecting a complex coupling between excited electrons and the disordered nuclear environment. To better understand this coupling and how nanoscale disorder affects the electronic dynamics in these materials we utilize numerical simulation. In this talk I describe our approach to unraveling the effects of nanoscale disorder on the dynamics of excitons, which utilizes atomistic simulation, coarse-grained models, and quantum dynamics.

Part II: "What Can Interfacial Water Molecules Tell Us About Solute Structure?”

The molecular structure of bulk liquid water reflects a molecular tendency to engage in tetrahedrally coordinated hydrogen bonding. At a solute interface water’s preferred three-dimensional hydrogen bonding network must conform to a locally anisotropy interfacial environment. Interfacial water molecules adopt configurations that balance water-solute and water-water interactions. The arrangements of interfacial water molecules, therefore encode information about the effective solute-water interactions. This solute-specific information is difficult to extract, however,  because interfacial structure also reflects water’s collective response to an anisotropic hydrogen bonding environment. Here I present a methodology for characterizing the molecular-level structure of liquid water interface from simulation data. This method can be used to explore water’s static and/or dynamic response to a wide range of chemically and topologically heterogeneous solutes such as proteins.