Electronic and Structural Properties of WO₃: A Systematic Hybrid DFT Study

Various hybrid functionals combined with both plane wave and localized basis sets have been used for a systematic study of the structural and electronic properties of all phases of WO₃. It is found that hybrid functionals work at least as well as the standard DFT/GGA functional in predicting lattice constants and equilibrium volumes. However, the adoption of hybrid functionals has the advantage to considerably improve the Kohn−Sham band gap which is always severely underestimated by the standard DFT calculations. The HSE06 functional in combination with a plane wave basis set describes well the band gap of WO₃, while the B3LYP functional associated with a localized basis set slightly overestimates it. The band gap can be made fully consistent with experiment by fixing the amount of Hartree−Fock exchange in the hybrid functional to 15%.