The structural, electronic, optical, elastic, and vibrational properties of GeS₂ using HSE03: a first-principle investigation

Density functional theory (DFT) has sparked intense interest in computational material predictions, especially in electronic band structure, optical dielectric functions, elastic moduli, and phonon calculations using non-local hybrid functionals. Using the first-principle-based calculations, a wide direct Γ-Γ bandgap E_g of 2.68 eV has been reported. Our partial density of states (PDOS) data also demonstrate that the substance exhibits metallic properties, based on the nonzero density of states at Fermi-level E_F. Still, what is more, our computational data show the orbital hybridization between Ge 4s² and S 3p⁴ electron states on the valence level, and a strong repulsive force occurs on both Ge and S p electron orbitals. The optical absorption coefficient calculated can reach up to 3 × 10⁵ cm⁻¹, indicating good material absorption. Our elastic information provided predicts substance ductility and ionic-covalency of the group IV-VI material. We have also added Vickers hardness and machinability index to our publication, for the sake of completeness. Finally, the slight system instability and weak coupling of the GeS₂ material have been observed, according to our phonon dispersion and density of phonon states plot.