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Data from: How unconventional oxidation state Au2+ is stabilized in halide perovskite Cs4Au3Cl12: A first-principles study of its polaron crystal nature

Morita, Kazuki1; Rappe, Andrew1

Published Jun 02, 2026 on Dryad. https://doi.org/10.5061/dryad.wwpzgmt0v

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Jun 02, 2026 version files 7.29 MB

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Abstract

Gold in crystalline compounds is typically only stable in oxidation states Au1+ and Au3+. Even compounds with nominal Au2+ usually disproportionate into Au1+ and Au3+. Recently, Cs4Au3Cl12 was synthesized, where gold took the 2+ state in the bulk. Here, we investigate this compound using first-principles calculations and show that stabilization of the Au2+ ion is through the formation of a polaron crystal. The electronic and phononic structure suggest that the bonding network can be interpreted as a collection of [Au2+Cl4]2- and [Au3+Cl4]1- square planar motifs, and the crystal lacks a smooth pathway for Au2+ to disproportionate into Au1+ and Au3+ without creating dangling bonds. The electronic states of Au are contained within each AuCl4 motif, which allows for the Au2+ state to be localized and isolated electronically. The Au2+-sites form an ordered structure, which is driven by a strong repulsive interaction between [Au2+Cl4]2- motifs due to their lattice distortion. By considering the redox reaction, we show that Cs4Au3Cl12 has the maximal density of Au2+, and further oxidation will induce a delocalized state. Cs4Au3Cl12 has distinctive electronic structure, with a narrow gap, isolated HOMO and LUMO bands strongly localized at the Au-sites, and magnetization at the Au2+-sites, making Cs4Au3Cl12 unique among quantum materials. Cs4Au3Cl12 can be a testbed to explore novel gold chemistry, and is an example system to control oxidation state through engineering of lattice distortions.