Optical properties of superhard BC5: First-principles calculations

BC5 is a newly synthesized superhard material. We present a systematic investigation of optical properties of BC5 in P3m1 and I-4m2 phases at ambient and high pressure in the framework of density functional theory with the generalized gradient approximation (GGA) in this paper. Optical properties such as dielectric function, refractive index, absorption, reflectivity and electron energy-loss spectrum are obtained successfully. The feature in the spectra of the optical parameters is discussed. Through calculation, we find BC5 is optically anisotropic. Moreover, the dielectric function exhibits a large change at 70 GPa pressure for P3m1 BC5 phase, but I-4m2 phase not, indicating the stable electronic structure that the I-4m2 phase possesses.