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Reunión de Usuarios y Desarrolladores de Métodos de Simulación de Aragón

Modelling realistic inorganic nanostructures; bridging the gap between theory and experiment

Prof. Stefan T. Bromley, ICREA-UB
Prof. Martijn Zwijnenburg, UCLondon

DATE OF EVENT : 05/09/2012       DURATION : 3 day(s)

LOCATION : ZCAM Campus Actur C/ Mariano Esquillor s/n Edificio I+D 50018 Zaragoza


SUMMARY :

The last twenty years have seen a colossal experimental effort to prepare and characterise ever smaller structures of inorganic materials down to as small as one nanometre in size. Such nanostructures have been demonstrated to often have widely different properties to that of the corresponding bulk material. As a result of these unique size-dependent characteristics inorganic nanostructures find application in numerous fields such as catalysis, solar cells, batteries and (bio)medical imaging. The same reduced size that makes these nanostructures interesting, however, also makes it difficult to understand the origins of their unique features fully by experiment alone. This knowledge gap is inherently linked to the difficulty of resolving the detailed atomic structures of nanostructured samples in experiment due to disorder and the associated broadening of diffraction and spectroscopic peaks.

Complementing experimental results with theoretical results is an attractive approach to closing the nanoscale knowledge gap. Here one would use computational chemistry calculations with realistic structural models of the nanostructure to gain atomistic insight into the fundamental processes underlying the size-dependency. Structural models would be obtained through global optimisation, where one aims to find the lowest energy structure for a given nanostructure, together with any information that can be obtained from experiment (e.g. composition, dimensionality, shape). Several groups have been developing such strategies in recent years using different global optimisation strategies (e.g. basin-hoping, genetic algorithms, simulated annealing, data mining) and have published “proof of principle” papers demonstrating that not only is it possible to reproduce experiment but also to successfully obtain microscopic insight unattainable by any other means. Most computational studies, however, at the moment still employ cuts from bulk structures or manually constructed clusters of unknown pedigree.

In the proposed workshop we plan to bring together for the first time not only people working on global optimisation of nanostructures but also computational chemist/physicists interested in modelling their properties, and experimental chemist and physicists who prepare and characterise nanostructures. This mix of experience, as also reflected in objective 1 (see below), is aimed at promoting the developments to people outside the primary global optimisation community who can directly benefit from these approaches in their research. In the proposed workshop we will also for the first time discuss strategies for how to extend the existing global optimisation methods (previously developed for studying nanostructures in vacuo) to handle nanostructures prepared in the presence of solvents and ligands. We finally hope also to shed light on the underexplored field of structure prediction for structures that are extended in one (e.g. nanotubes) or two dimensions (e.g. thin films) and nanosized in the other dimensions.