Impact of hubbard u correction on the band gap energy of LiNbO3

The electronic properties of lithium niobate (LiNbO3) were investigated using first-principles calculations based on density functional theory (DFT). The simulations were carried out using the CASTEP code with the LDACAPZ functional, both with and without the inclusion of Hubbard U correction (LDA+U). A hexagonal LiNbO3 structure with space group R3c was used. Electronic properties were analyzed through band structure and density of states calculations. The Hubbard U value was varied from 0 to 14 eV, and its impact on the band gap was studied. The calculated band gap energies were 3.506 eV (LDA) and 3.751 eV (LDA+U), with the closest agreement to the experimental band gap observed at U = 13 eV. The application of DFT+U improved the description of electronic structure and optical transitions. The computed values were in good agreement with available experimental data and previous reports, validating the effectiveness of the DFT+U approach for modelling LiNbO3