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Theoretical and computational study of high pressure structures in barium

Stewart K. Reed·Graeme J. Ackland
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Abstract

Recent high pressure work has suggested that elemental barium forms a high pressure self-hosting structure (Ba IV) involving two `types' of barium atom. Uniquely among reported elemental structures it cannot be described by a single crystalline lattice, instead involving two interpenetrating incommensurate lattices. In this letter we report pseudopotential calculations demonstrating the stability and the potentially disordered nature of the `guest' structure. Using band structures and nearly-free electron theory we relate the appearance of Ba IV to an instability in the close-packed structure, demonstrate that it has a zero energy vibrational mode, and speculate about the structure's stability in other divalent elements.

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Stewart K. Reed, Graeme J. Ackland. 2000-05-02. Theoretical and computational study of high pressure structures in barium. https://doi.org/10.1103/physrevlett.84.5580

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