Structure and Electronic Properties of Transition-Metal/Mg Bimetallic Clusters at Realistic Temperatures and Oxygen Partial Pressures


Composition, atomic structure, and electronic properties of TMxMgyOz clusters (TM = Cr, Ni, Fe, Co, x + y ≤ 3) at realistic temperature T and partial oxygen pressure pO2 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 at the hybrid density-functional level of theory. On analyzing a large set of data, we find that the fundamental gap Eg of the thermodynamically stable clusters are strongly affected by the presence of Mg-coordinated O2 moieties. In contrast, the nature of the transition metal does not play a significant role in determining Eg. Using Eg of a cluster as a descriptor of its redox properties, our finding is against the conventional belief that the transition metal plays the key role in determining the electronic and therefore chemical properties of the clusters. High reactivity may be correlated more strongly with oxygen content in the cluster than with any specific TM type.

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Shikha Saini and Prof. Saswata Bhattacharya

Department of Physics