Accurate Prediction of Opto‐Electronic Properties of WO₃: A Beyond‐DFT Study

Photocatalytic materials, such as , continue to be a focus of research due to their potential in energy harvesting applications, which depend on effective photon absorption and exciton processes governed by electronic structure. In this study, we examine the electronic and optical properties of orthorhombic‐phase using first‐principles calculations. To address the issue of band gap underestimation in density functional theory (DFT), the HSE06 hybrid functional was applied which yield a more accurate band gap in materials by incorporating a portion of exact exchange from Hartree–Fock theory. The inclusion of exact exchange improves the treatment of electron‐electron interactions, leading to band gap predictions that align more closely with experimental results. Optical properties were calculated through the independent particle approximation (IPA) and the Bethe–Salpeter Equation (BSE), enabling a detailed comparison with experimental data. Our findings show that the BSE approach, which accounts for electron‐hole interactions, aligns more closely with experimental absorption measurements than IPA, underscoring the significant role of excitonic effects in accurately describing ’s optical response. This study demonstrates that using hybrid functional corrections in combination with the BSE framework provides a reliable approach for assessing and predicting the photocatalytic efficiency of in its orthorhombic phase. This is the first theoretical‐experimental benchmark of orthorhombic using both HSE06 and BSE, highlighting its potential as a visible‐light‐active photocatalyst.