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DY: Fachverband Dynamik und Statistische Physik

DY 4: Statistical Physics (general) II

DY 4.2: Vortrag

Montag, 22. März 2010, 14:15–14:30, H47

Molecular dynamics simulation of nucleation in binary systems — •Stephan Braun and Thomas Kraska — University of Cologne, Department of Chemistry, Luxemburger Str. 116, D-50939 Köln

The vapour-liquid nucleation of the binary system n-nonane/methane is investigated by molecular dynamics simulation. The supersaturation of the system is achieved by cooling down the system during expansion in order to closely mimic the real process which is for example applied in practice to separate heavy compounds from natural gas.

The expansion is simulated via a stepwise enlargement of the simulation box with short equilibration runs in between. From these simulations one obtains several details of the nucleation process, which are difficult or impossible to obtain from experiments. These are the early stages of nucleation and growth taking place on the nanosecond time scale. The simulations provide information on the way how binary supercritical systems nucleate on the molecular scale as well as on nucleation rates and critical cluster sizes. Since the n-nonane clusters contains a large amount of methane molecules the composition of the clusters is analysed with respect to the mole fractions to get a better understanding of the properties of the clusters.