The structural, elastic, electronic and optical properties of orthorhombic FeX2 (X=S, Se, Te)

The orbital-projected band structures onto Se-p (pink circles), Fe-t2g (green circles) and Fe-eg (blue circles) states of orthorhombic FeSe2. The Fermi level EF is set at zero, the horizontal black dashed lines denote the energy positions of conduction band minimum and valence band maximum. The size of symbol represents the contribution weight of the corresponding orbital.167