First-principles study on the structural, elastic, electronic and optical properties of LiNbO3

The structural, electronic, elastic, mechanical and optical properties of technologically important lithium niobate (LiNbO 3 ) have been investigated by using the first-principle calculations based on density functional theory (DFT) implemented in the CASTEP code. The lattice constants and unit cell volume were calculated from the optimized unit cell, which were in well agreement with the reported theoretical as well as experimental values. Bulk modulus B , Young's modulus Y , shear modulus G , Poisson's ratio σ , elastic anisotropy A and compressibility K were determined based on the computed values of independent elastic constants ( C 11 , C 12 , C 13 , C 14 , C 33 , C 44 and C 66 ). Electronic band structure and density of states (DOS) demonstrated its semiconducting nature showing a band gap of 3.54 eV. Furthermore, several optical properties, such as absorption coefficient, reflectivity, refractive index, dielectric function, optical conductivity and electron energy loss function have been calculated.