Simulating the nucleation of water/ethanol and water/n-nonane mixtures: mutual enhancement and two-pathway mechanism.
A combination of the aggregation-volume-bias and configurational-bias Monte Carlo algorithms and the umbrella sampling technique was applied to investigate two different binary vapor-liquid nucleation systems: water/ethanol and water/n-nonane. The simulations are able to reproduce the different nonideal nucleation behavior observed experimentally for these two systems, i.e., the mutual enhancement of nucleation rates for water/ethanol mixtures and the two-pathway nucleation for water/n-nonane mixtures. Structural analysis provides microscopic explanations for the observed nucleation behavior. In particular, the simulations show a large and size-dependent surface enrichment of ethanol in the water/ethanol droplets, which confirms the previous experimental interpretation for this system. The immiscibility observed even for small water/n-nonane clusters causes the two-pathway nucleation mechanism.
Chen
Bin
B
Center for Molecular Modeling and Department of Chemistry, University of Pennsylvania, 231 S. 34th Street, Philadelphia, Pennsylvania 19104-6323, USA. binchen@cmm.chem.upenn.edu
Siepmann
J Ilja
JI
Klein
Michael L
ML