AAAR 31st Annual Conference
October 8-12, 2012
Hyatt Regency Minneapolis
Minneapolis, Minnesota, USA
Abstract View
Nucleation Free Energy Landscapes: Sensitivity to Force Fields and Influence of Salt Nanoparticles
SAMUEL KEASLER, Christopher Hogan Jr., Ilja Siepmann, University of Minnesota
Abstract Number: 427 Working Group: Aerosol Nucleation: From Clusters to Nanoparticles
Abstract Nucleation free energy (NFE) landscapes provide detailed information on the pathway of nucleation processes. Advanced Monte Carlo algorithms allow for the precise determination of the NFE landscape. Such computed NFE landscapes are known to be very sensitive to details in the force field used to described the intermolecular interactions. Using the unary nucleation of water as an example, it is shown that the sensitivity of the NFE profile to the force field can be dramatically reduced by comparing the simulation results at the same reduced temperature and supersaturation instead of the same absolute temperature and absolute pressure (or number density). That is, the phase diagram is much more sensitive to details of the force field than the nucleation process. The aggregation of water onto salt nanoparticles is an important process in atmospheric chemistry, yet efforts to better understand it have been hindered by the difficulty of isolating and characterizing the small transient clusters involved. Monte Carlo simulations are carried to probe the nucleation of water around Na$_nCl$_m nanoclusters. The effect of size and charge on the NFE landscape are discussed.