The Study of Hubbard U Correction on Structural, Electronic and Optical Properties of LiNbO3

Abstract

The structural, electronic, and optical properties of lithium niobate (LiNbO₃) are investigated using a first-principles study. The first-principles calculation in this work is performed using CASTEP computer code with GGA-PBEsol, LDA, GGA-PBEsol+U, and LDA+U methods. The crystal structure used for this calculation was hexagonal symmetry LiNbO₃ with a space group of R3c. The band structure and density of states are calculated to analyze the electronic properties of LiNbO₃. The band gap energy calculated is found to be 3.483 eV and 3.506 eV for GGA-PBEsol and LDA, respectively. The Hubbard U correction is performed using U values varies from U= 0 eV until U= 14 eV. The  Hubbard U value for the band gap of LiNbO3 which is close to the experimental band gap is observed at 10 eV and 11 eV for GGA-PBEsol+U and LDA+U. The band gap obtained after Hubbard U correction are 3.681 eV and 3.751 eV for both methods. The optical properties such as dielectric function, refractive index, and absorption coefficient of LiNbO₃ before and after Hubbard U correction are also analyzed.