|11月28日学术报告：Combining Theory and Experiment to Determine the Structures of Gas Phase Metal Clusters
|学术报告题目：Combining Theory and Experiment to Determine the Structures of Gas Phase Metal Clusters
报告人：Roy Johnston, Royal Society University Research Fellow, University of Sussex
It has been shown that for many nanoparticles a two stage approach, namely performing global optimisation using an empirical many-body potential, followed by local minimisation of a variety of candidate structures at a higher level of theory - usually Density Functional Theory (DFT) - can lead to reliable cluster geometries and chemical ordering (for alloy nanoparticles [1,2]). However, there are limitations to the use of empirical potentials - for example, they do not reproduce the planar structures of small Au-containing clusters  and there are some systems (e.g. Sn. Pb and Bi) for which no reliable empirical potentials exist.
In this presentation, a novel genetic algorithm based approach will be introduced for the direct global optimisation of small clusters directly at the DFT level (with DFT calculations performed using the PWscf code within QuantumEspresso) [4,5]. These calculations will be combined with the results of cluster molecular beam deflection experiments to determine the structures of experimentally produced neutral gas phase bismuth-doped tin clusters . Recent results will also be presented combining DFT-GA minimisation and TD-DFT calculations to rationalise the UV-visible spectra of cationic Ag-Au clusters .
Prof. Roy Johnston
Roy Johnston’s research spans the fields of computational nanoscience and nature-inspired computation. Examples include: the study of elemental and bimetallic clusters; the application of genetic and other nature-inspired algorithms to optimization problems in chemistry (including GA-DFT optimization); simulating the optical spectra and electron microscopy images of metal nanoparticles; DFT studies of the geometries, electronic structures, and reactivity of metal clusters and nanoalloys; and developing techniques for visualizing and analyzing the complexity of energy landscapes. He is the author of one book and editor of three others and has published over 190 journal articles and reviews.