James Kindt

Professor James Klindt, Emory University. "Cluster Free Energies from Simple Simulations of Small Systems, with Help from Number Theory."  Harvard/MIT/BU Theoretical Chemistry Talk.Abstract:  This lecture will start with a review of the statistical thermodynamic basis for the conventional treatment of chemical equilibrium, and a discussion of how this treatment breaks down for small systems. fundamental derivation inspired a “brute-force” strategy based on explicit enumerations of integer partitions, to allow ensemble-averaged equilibrium concentrations to be related to cluster free energies even for small systems. A more elegant and computationally cheaper approach called “PEACH” (Partition-Enabled Analysis of Cluster Histograms) formulated in collaboration with members of the number theory group at Emory, will then be presented. Evidence from coarse-grained simulations of an anionic surfactant will be presented to validate the PEACH approach. A case where the method worked suspiciously well (nanodroplet formation from methyl t-butyl ether) will then be discussed, along with how it led us to a simple strategy to reduce complications from non-ideal effects in aggregation equilibria. Finally, PEACH analysis of equilibria involving NaCl clustering in three solvent environments will be used to illustrate qualitatively different pathways towards formation of an ordered precipitate from supersaturated solution.