The features of the semiconducting state formation in oxysulfostibnites of the rare earth metals GdSbS₂O, DySbS₂O, HoSbS₂O, and ErSbS₂O have been investigated. Our theoretical calculations were performed in the framework of the GGA+U method accounting for strong electron correlations in the 4f shell of rare earth metals and they showed that these compounds, GdSbS₂O [1], DySbS₂O, HoSbS₂O, and ErSbS₂O [2], are semiconductors with a small direct gap at high-symmetry point X. For the first time, it was found that for the band gap formation in the rare-earth-metal oxysulfostibnites, it is important both to optimize the crystal structure and to take into account the spin--orbit coupling. The rare-earth-metal oxysulfostibnites, along with their layered structural analogues oxysulfides, due to their distinctive properties, can be widely used in biomedicine, photoluminescence, and other fields. Our calculations were performed on the Uran supercomputer at the Institute of Mathematics and Mechanics of the Ural Branch of the Russian Academy of Sciences. This research was carried out within the framework of the state assignment of the Ministry of Education and Science of Russia, theme “Electron”, No. 122021000039-4.

1. S.T. Baidak, A.V. Lukoyanov, “Semimetallic, half-metallic, semiconducting, and metallic states in Gd-Sb compounds”, International Journal of Molecular Sciences 24, 8778 (2023), https://doi.org/10.3390/ijms24108778
2. S.T. Baidak, A.V. Lukoyanov, “Formation of a semiconductor state in oxysulfostibnites RSbS₂O at R = Dy, Ho, Er”, Journal of Experimental and Theoretical Physics (accepted, 2024).