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 it abinitio plane-wave pseudopotential density functional theory methodin the generalised gradient approximation (GGA) forexchange-correlation interaction. The electronic band structure andthe pressure dependence of the total and partial densities of stateunder pressure are successfully described. Our calculations showthat the ZB BeS has large and indirect band gaps associated with(Γ → X) transitions in ambient conditions. Theresults obtained are consistent with the experimental dataavailable and other calculations. The optical properties, includingdielectric function, energy-loss function, complex refractive index,reflection and absorption spectra, are investigated and analysed atdifferent external pressures. The results suggest that the opticalabsorption appears mostly in the ultra-violet region and the curveof refractive index shift toward high energies (blue shift) withpressure increasing.