"Nucleation at the nanoscale: pathways of phase transitions in small systems"
PHYSICS DEPARTMENT COLLOQUIUM
Nucleation at the nanoscale: pathways of phase transitions in small systems Christopher Dellago
Universität Wien, Vienna, Austria
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.
April 24, 2013 (Wednesday)