Properties of the gold oxides Au2O3 and Au2O: First-principles investigation

Density-functional theory DFT calculations have been carried out using the generalized gradient approximation GGA to investigate the atomic and electronic structure and stability of the gold oxides Au2O3 and Au2O. We find that Au2O3 is a semiconductor and is more stable than Au2O, which is an endothermic system, and only metastable. The higher stability of Au2O3 is attributed to a greater hybridization of Au 5d and O 2p states throughout the valence-band region as compared to Au2O. The highest energy, oxygen related normal vibrational mode is slightly higher in Au2O3 as compared to Au2O. Au2O is predicted by DFT-GGA to be metallic; calculations performed, however, using the screened-exchange local-density approximation find that it has a band gap of 0.83 eV; thus, it is a direct narrow-band-gap semiconductor.