DFT based studies on the structural, electronic and optical properties of LiNbO₃ using some hybrid techniques

Abstract

Structural, electronic, and optical properties of ferroelectric material, Lithium niobate (LiNbO3) are explored and studied using two different techniques namely, OLCAO-MGGA-TB09+c and OLCAO-GGA-PBES + U under the framework of density functional theory (DFT). The electronic properties such as band diagram, the effective mass of charge carriers, the total density of state (TDOS), and partial density of state (PDOS) are investigated in depth. Band gap values obtained using MGGA-TB09+c is 3.79 eV whereas, it is 3.78 eV for GGA-PBES + U. Furthermore, several optical properties such as dielectric constant, reflectivity, refractive index, optical conductivity, loss function, and absorption coefficient have also been extracted. It is seen that the results so obtained are consistent with experimental data which shows the soundness of our calculations. From the statistical analysis, it is found that both the techniques provide very good results on electronic and optical properties of LiNbO3 compared to existing computational work as both give an approximation of experimental data. The methods presented here will be useful for researchers to get accurate results on structural, electronic, and optical properties of other materials.

Vibrational Spectra and Electro‐Optic Effect of Ferroelectric LiNbO3Crystal

“…[9] Though showing the vital importance in modern day technologies, the basic optic and especially EO properties studied from high-accuracy first-principle calculations are still not satisfactory. [10][11][12][13][14][15][16][17][18][19][20][21][22][23][24][25] Early calculations based on density-functional theory (DFT) with local-density approximation (LDA)-or generalized gradient approximation (GGA)-type functionals always underestimate the bandgap, hence overestimate most of the response functions, for example, dielectric constants, and second-order susceptibilities including second harmonic generation (SHG) and EO coefficients. Previous calculations in this category often use an unphysical so-called scissor operator to manipulate the bandgap to match the observed optic transmission cutoff or obtained by separate calculations.…”