A global optimisation study of the low-lying isomers of the alumina octomer (Al${}_2$O${}_3$)${}_8$

Abstract

We employ the Monte-Carlo Basin-Hopping (MC-BH) global optimisation technique with inter- atomic pair potentials to generate low-energy candidates of stoichiometric alumina octomers ((Al${}_2$O${}_3$)${}_8$). The candidate structures are subsequently refined with density functional theory calculations employing hybrid functionals (B3LYP and PBE0) and a large basis set (6-311+G(d)) including a vibrational analysis. We report the discovery of a set of energetically low-lying alumina octomer clusters, including a new global minimum candidate, with shapes that are elongated rather than spherical. We find a stability limit for these and smaller-sized clusters at a temperature of $T\simeq 1300-1450$ K corresponding to a phase transition in liquid alumina.

arXiv comment19 pages, 9 figures, accepted for publication

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