First-principles calculations for electronic and optical properties of the zinc-blende structured BeS compound under pressure

The electronic and the optical properties of the cubic zinc-blende (ZB) BeS under high pressure have been investigated by using ab initio plane-wave pseudopotential density functional theory method in the generalised gradient approximation (GGA) for exchange-correlation interaction. The electronic band structure and the pressure dependence of the total and partial densities of state under pressure are successfully described. Our calculations show that the ZB BeS has large and indirect band gaps associated with (Gamma -> X) transitions in ambient conditions. The results obtained are consistent with the experimental data available and other calculations. The optical proper-ties, including dielectric function, energy-loss function, complex refractive index, reflection and absorption spectra, are investigated and analysed at different external pressures. The results suggest that the optical absorption appears mostly in the ultra-violet region and the curve of refractive index shift toward high energies (blue shift) with pressure increasing.