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Physics Colloquium - Dr Elke Pahl

Monday, 8 May 2017 9:21am

Physics Department

Dr Elke Pahl

Senior Lecturer

Centre for Theoretical Chemistry and Physics

Institute of Natural and Mathematical Science

Massey University

"Melting of Atomic Nano-Clusters and Extended Systems: Simulations with Accurate Inteaction Potentials"

Nano-clusters are wonderful models for studying the emergence of condensed matter phenomena like the melting phase transition by increasing atom number, so to say in a bottom-up approach. Aggregates of 10s to 1000s of particles exhibit very complex potential energy surfaces describing the energy in dependence of the positions of the atoms, with many close-lying minima. In order to simulate the melting process, we need very accurate interaction potentials and have to explore the resulting potential landscapes extensively at a range of temperatures spanning the melting transition. While we use highly accurate quantum-chemical methods for the atomic interactions, so-called parallel-tempering Monte Carlo simulations or alternatively 'interface-pinning' molecular dynamics methods allow for an efficient sampling of the surfaces.

After an introduction into the topic and the approach taken, I will present our contributions to questions like: Can concepts of statistical physics, derived for a very large number of particles, still be applied to the description of clusters with only a few atoms? Is an extrapolation of cluster results to the bulk behaviour possible? How does ultra-high pressure influence melting? And finally, why is mercury the only liquid atomic metal at room temperature?

WHEN: Monday 8 May 2017
WHERE: Room 314, Science 3 Building
TIME: 3.00 pm–4.00 pm

All interested are welcome to attend

Light refreshments to follow in Common Room