Hybrid density functional study of the structural, bonding, and electronic properties of bismuth vanadate

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.