Berlin 2018 – wissenschaftliches Programm

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MM: Fachverband Metall- und Materialphysik

MM 34: Nanomaterials

MM 34.1: Vortrag

Mittwoch, 14. März 2018, 11:45–12:00, H 0106

Equilibrium nanoparticle shapes for any size from atomistic simulations — •Magnus Rahm and Paul Erhart — Department of Physics, Chalmers University of Technology, Gothenburg, Sweden

In the pursuit of complete control over morphology in nanoparticle synthesis, knowledge of the thermodynamic equilibrium shapes is a key ingredient. While the classical Wulff construction provides a solution in the continuum limit, the small particle regime has been studied using global minimum energy search method reaching particle diameters of roughly 1 or 2 nm. The experimentally important intermediate size regime, however, has largely remained elusive. Here, we present an algorithm, based on atomistic simulations in a constrained thermodynamic ensemble, that efficiently predicts equilibrium shapes for any number of atoms in the range from a few tens to 10,000, corresponding to diameters between approximately 1 and 7 nm. We apply the algorithm to Cu, Ag, Au and Pd and reveal an energy landscape that is more intricate than previously suggested. In particular, we demonstrate that, as a result, the transition from icosahedral particles to decahedral and further into FCC particles occurs very gradually. One must thus expect more than one shape in thermodynamic equilibrium and not only for for kinetic reasons.

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