Dresden 2017 – wissenschaftliches Programm

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MM: Fachverband Metall- und Materialphysik

MM 22: Poster session I

MM 22.21: Poster

Montag, 20. März 2017, 19:00–20:00, P4

Equilibrium shapes of large nanoparticles: Wulff-construction on the atomic scale — •Magnus Rahm and Paul Erhart — Department of Physics, Chalmers University of Technology, Gothenburg, Sweden

Finding the equilibrium shape of nanoparticles is a great challenge. While the classical Wulff construction provides a solution given a set of pre-defined surface energies in the continuum limit, the predictions are unreliable for medium sized nanoparticles when edge and corner sites have a sizeable effect the total energy. On the other end, numerous efforts have been made to find the global minimum shape without restrictions to crystal lattices, yet the complexity of the resulting optimization problem limits predictions to nanoparticle sizes of a few hundred atoms or less. Here, we explore the middle ground between large nanoparticles, which can be captured using the Wulff construction and very small nanoclusters. To this end, a computational technique based on Monte Carlo sampling in the variance-constrained semigrand canonical ensemble has been developed. We apply the method to a number of transition metals and demonstrate the flatting of the energy landscape with increasing particle size and describe its transition to the Wulff construction in the continuum limit. The method is also applied to particles with icosahedral symmetry, which are shown to have a much more rugged energy landscape and thus are more likely to exhibit a discontinuous size distribution.