Influence of different exchange correlation potentials on band structure and optical constant calculations of ZrGa2 and ZrGe2 single crystals

The all-electron full potential linearized augmented plane wave method was used to solve the Kohn Sham DFT equations. We have employed different approximations for the exchange correlation potentials, namely: LDA, GGA and EVGGA, and insignificant effect on the band structure and the density of states were found. Calculations show that there is a significant difference in the band dispersion with replacement of Ga by Ge that is attributed to the fact that in the ZrGe2 compound Zr atom is situated at 4c site and two Ge atoms are situated at 4c site. Whereas for ZrGa2 compound Zr is located at 4g site and the three Ga atoms are situated at 4h, 2c and 2a sites, respectively. There exists strong hybridization between the states. Moving from ZrGa2 to ZrGe2 has significant influence on the magnitudes and the peak positions of states. The optical properties of the two compounds were studied and analyzed.