Structural, elastic, electronic and optical properties of beryllium chalcogenides BeX (X = S, Se, Te) with zinc-blende structure

The structural stability, elastic, electronic structures and optical properties of the BeX (X = S/Se/Te) cubic compounds in zinc-blende (B3) structure have been investigated using a pseudopotential plane wave (PP-PW) method within the generalized gradient approximation (GGA) and the local density approximation (LDA). The use of the hybrid functional sX-LDA leads to considerably improved electronic properties compared to standard GGA and LDA approaches. The calculated lattice parameters and bulk modulus agree reasonably with the previous results. The second-order elastic constants have been calculated and we also obtained phase transition pressure of BeX from B3 to NiAs (B8) structures. The enthalpy of formation, band structure, density of states and electric charge density is as well given. On the other hand, an accurate calculation of linear optical functions (the dielectric function, refraction index and reflectivity) is performed. The results obtained are compared with other calculations and experimental measurements.