Theoretical design of stable small aluminium-magnesium binary clusters

Authors

Edison Osorio
Alejandro Vasquez
Elizabeth Florez
Fanor Mondragon
Kelling J. Donald, University of RichmondFollow
William Tiznado

DOI

10.1039/c2cp42015e

Abstract

We explore in detail the potential energy surfaces of the Al_xMg_y (x, y = 1–4) systems as case studies to test the utility and limitations of simple rules based on electron counts and the phenomenological shell model (PSM) for bimetallic clusters. We find that it is feasible to design stable structures that are members of this set of small Al–Mg binary clusters, using simple electron count rules, including the classical 4n + 2 Hückel model, and the most recently proposed PSM. The thermodynamic stability of the title compounds has been evaluated using several different descriptors, including the fragmentation energies and the electronic structure of the systems. Three stable systems emerge from the analysis: the Al₄Mg, Al₂Mg₂ and Al₄Mg₄ clusters. The relative stability of Al₄Mg is explained by the stability of the Al₄^2- subunit to which the Mg atom donates its electrons. Here the Mg²⁺ sits above the aromatic 10 π-electron Al₄^2- planar ring. The Al₂Mg₂ and Al₄Mg₄ clusters present more complicated 3D structures, and their stabilities are rationalized as a consequence of their closed shell nature in the PSM, with 10 and 20 itinerant electrons, respectively.

Document Type

Article

Publication Date

2013

Publisher Statement

Copyright © 2013 Royal Society of Chemistry. This article first appeared in Physical Chemistry, Chemical Physics 15 (2013), 2222-2229.

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Recommended Citation

Osorio, Edison, Alejandro Vasquez, Elizabeth Florez, Fanor Mondragon, Keilling J. Donald, and William Tiznado. "Theoretical Design of Stable Small Aluminium–magnesium Binary Clusters." Physical Chemistry, Chemical Physics 15 (2013): 2222-229. doi:10.1039/c2cp42015e.