Study of the optical properties of pristine hexagonal boron nitride using the DFT method

Abstract

Density Functional Theory (DFT) was used based on the Generalized Gradient Approximation (GGA) as it was conducted in the last stage for each studied case to obtain the optical properties such as absorption coefficients, reflection, refraction, conductivity and dielectric constant. And we proved through our study on the large unit cell of pristine boron nitride that the electronic energy gap is indirect, the energy gap(E_g)was calculated for the optical absorption coefficient which is equal to 4eV. Then the highest value of reflectivity was recorded at 8.5 eV, which is estimated at (0.0494). The value of the refractive index is 1.16, then the refractive index increases with the increase in the energy of the photons to reach 1.4 at the frequency eV5 in the ultraviolet region. The dielectric constant starts at 1.34. The conductivity values ​​are increasing at the frequency of 14.2 eV, which corresponds to 1.4.