(536b) On Methods for Computing Free Energy Differences and Barriers in Soft Materials Undergoing Ordering Transitions

After reviewing some of the general statistical mechanical principles involved in modeling free energies and how the connection among some old and new methodological variants are often overlooked (an issue that generalized frameworks try to remedy), I will describe selected methods that our group has developed to efficiently evaluate free energy changes associated with different phases and with the transition barriers between phases. These include methods for optimizing multistage ensemble simulations, for tracing phase boundaries, and for estimating free-energy nucleation barriers for situations posing significant challenges to conventional methods. I will illustrate the usefulness of these methods through sample applications concerning the self-assembly behavior of novel particle-based crystals and oligomeric mesophases. I will conclude by pointing out some of the outstanding methodological challenges, e.g., associated with mapping and inverse-mapping the behavior of coarse and fine-grained models.