Computational chemistry studies of sulfuric acid clustering ? first-principle nucleation rates from dynamic cluster models Theo Kurtén Department of Physical Sciences University of Helsinki We combine quantum chemical evaporation rates with dynamic cluster modeling in order to study the nucleation behavior of a system containing sulfuric acid, ions and nitrogen bases (ammonia and dimethylamine). Despite the lack of any fitting parameters, as well as the limitation of our cluster dataset to clusters containing four acids or less, our computed results match the experimental (laboratory and field) observations fairly well. The model results are useful for comparing e.g. neutral base-enhanced and ion-induced sulfuric acid nucleation over a wide range of different conditions, some of which may be quite difficult to attain experimentally. Time: Wednesday, November 23 at 14:15 Place: 1525-223, Department of Physics and Astronomy Preben Hvelplund and Steen Brøndsted