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Colloquium: April 24, 2013

Christoph Dellago*
Nucleation at the nanoscale:
pathways of phase transitions in small systems
Day Time Place
April 24, 2013 Wednesday 16:00 EE01

Host: Balazs Hetényi

ABSTRACT — Under suitable conditions, first order phase transitions such as the freezing of a liquid or the structural transformation of a solid occur via a nucleation and growth mechanism, in which a nucleus of the stable phase is formed in the metastable phase. For systems with sizes in the nanometer regime, the nucleation mechanism and its kinetics are strongly affected by finite size effects. I will address this issue using melting/freezing of gold nanoparticles, the Wurtzite-to-rocksalt transition in CdSe nanocrystals and the magnetization reversal in a finite Ising model as illustrative examples. Based on the results of transition path sampling simulations, I provide a picture of the transition mechanism paying particular attention to the structure of the critical nuclei. The role of the reaction coordinate in the investigation of the transition mechanism is discussed.

*Universität Wien, Vienna, Austria

The Physics Colloquia are designed to address a non-specialist, broad audience and introduce topics of contemporary research through lectures by leading experts. We warmly invite all members of the student body, including undergraduates enrolled in any programme.

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