Abstract
The structure and property prediction of metal oxides can significantly be improved by incorporating exact Hartree-Fock (HF) exchange into density functional theory (DFT), which is the so-called hybrid DFT. We explored the impact of HF exchange inclusion on the predicted structural, bonding, and electronic properties of bismuth vanadate (BiVO${}_{4}$), with particular attention to the difference between its monoclinic and tetragonal scheelite phases. The applied exchange-correlation (xc) functionals include the gradient corrected Perdew-Burke-Ernzerhof (PBE) and the PBE-HF hybrid functionals with HF exchange amounts of 10$%$, 25$%$, and 50$%$. We find that the PBE-HF25$%$ yields a monoclinic structure in very close agreement with the experimentally determined structure, while the PBE-HF50$%$ tends to overestimate the monoclinic distortion and the PBE/PBE-HF10$%$ can hardly identify a distinct monoclinic configuration at ambient conditions. Electronic structure analysis reveals that the increasing monoclinic distortion with the amount of HF exchange is related to the enhancement of hybridization between Bi 6$s$-O 2$p$ antibonding states and unoccupied Bi 6$p$ states. The bonding mechanisms and band structures of the monoclinic and tetragonal phases of BiVO${}_{4}$ were also investigated, and we discuss how the predictions are sensitive to the xc functional choice.
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