Catalytic activity in metal oxides is generally localized at edge and surface defects. Dilution effects and the dynamic nature of defect and surface-absorbate structure complicate studies of these sites in bulk metals. Metal oxide clusters can be used to serve as prototype systems, aided by the use of quantum chemical calculations to identify the structure and relevant electronic spin states. However, in many cases these calculations exhibit severe spin contamination. Although it has long been recognized that spin contamination often adversely affects the quality of energy calculations (at both SCF and post-SCF levels), the affect of spin contamination on the shape of the potential energy surface is often thought to be minor. This presentation describes our recent progress towards an efficient approximate spin projection model including analytic energy derivative implementations.. We show how this method can be applied to metal oxide clusters to reveal some significant changes in predicted geometries and spin state orderings to give better insight into the energies and properties of metal oxide catalysis.

Metal oxide clusters: The need for spin pure states

248th National Meeting (2014)

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