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要旨

Composition, atomic structure, and electronic properties of TM_xMg_yO_z clusters [transition metal (TM) = Cr, Ni, Fe, and Co, x + y ≤ 3] under realistic temperature T and oxygen partial pressure p_O2 conditions are explored using the ab initio atomistic thermodynamics approach. The low-energy isomers of the different clusters are identified using a massively parallel cascade genetic algorithm on the hybrid density-functional theory level. On analyzing a large set of data, we find that the fundamental gap E_g of the thermodynamically stable clusters is strongly affected by the presence of Mg-coordinated O₂ moieties. By contrast, the nature of the TM does not play a significant role in determining E_g. Using E_g of a cluster as a descriptor of its redox properties, our finding is against the conventional belief that the TM plays a key role in determining the electronic and therefore chemical properties of the clusters. High reactivity may be correlated more strongly with the oxygen content in the cluster than with any specific TM type.