Advanced MD simulations of heterogeneous nucleation of binary colloids

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We plan to investigate heterogeneous nucleation in a 3D colloidal model system consisting of spherical particles. These colloids can interact via different potentials; as a test system for our methods we are using uncharged spheres interacting via Lennard-Jones potential, confined by planar or structured walls to facilitate heterogeneous nucleation. In the second funding period, we plan to extend our investigations to charged spheres, thereby mimicking the experimental systems proposed by P. Wette and H. J. Sch¨ope. We want to study heterogeneous nucleation in these systems by introducing smooth or structured charged walls, or by investigating a bidisperse system consisting of small and large charged spheres, in which the big spheres can both act as nucleation seeds or counteract nucleation, depending on size ratio of the binary suspension. In our studies we will employ advanced MD algorithms using forward-flux and umbrella sampling, that we develop in collaboration with the groups of Schilling and Horbach. Both methods have proved to be very efficient for nucleation studies, and should enable us to extract nucleation rates, size and shape of the critical nuclei, free energy barriers, and simultaneously should give us insight into the nucleation pathways. At a later stage we plan to investigate the role of hydrodynamic interactions on the nucleation kinetics.