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Siegel der Universität
Department für Chemie - Arbeitsgruppe Prof. Strey

Molekulardynamische Simulationen von Argon-Clustern

Stephan Wonczak, November 2001

Homogenous nucleation of argon and the behaviour of small clusters is investigated using molecular dynamics simulations. To this end a program package named cluster was developed and optimized. it is shown that nucleation can indeed be observed in simulations if the supersaturation is high enough (S ? 10). The obsered nucleation rates were on the order of J = 1024 to 1028 cm-3s-1. The growth process of the clusters could be observed up to a diameter of some 10 nm. In systems with more than one cluster formed during nucleation ageing processes like coalescence were observed. Using the resulting liquid droplets a vapor pressure curve was simulated in a temperature range between 70 K and 90 K. To rescale the vapor pressure over a curved surface into the pressure over a flat surface an improved curvature correction was developed. It takes the supersaturated conditions in the gas phase into account. The simulated vapor pressure data shows a good agreement with experimental data. Finally condensation and evaporation rates of small clusters were obtained as a function of cluster size and temperature. These microscopic kinetic data are of interest for the development of better theories of nucleation.