Winkler, B., Pickard, C. J., Segall, M. D. and Milman, V. (2001) Density-functional study of charge disordering in Cs2Au(I)Au(III)Cl-6 under pressure. Physical Review B, 63 (21). DOI 214103.

Abstract

We demonstrate that density-functional theory can be used to study the charge-order/disorder transition in Cs2Au(I)Au(III)Cl-6. The ground-state structure of this mixed-valence compound is reproduced with satisfactory accuracy, and a discontinuous phase transition is calculated to occur at about 6-10 GPa, in agreement with published experimental values. The precision of the calculations and of previously published experiments is insufficient to unambiguously determine whether the transition is from I4/mmm to P4/mmm, or proceeds directly into a cubic phase with space group Pm (3) over barm. Irrespective of the symmetry of the phase appearing at 6-10 GPa, the calculations show that the pressure-induced structural changes are accompanied by a charge disordering, and that all gold atoms are in the single-valence state, Au2+, in the high-pressure phase.

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