Figure 6

(a) The spin polarized energy band structures of Cu³⁺ ion in ZnO. The inset in the spin up band structure shows close up of the Cu 3d-t₂ branch near Γ point. For clarity the relative position of Cu 3d orbitals are drawn schematically in (b). (c) The spatial distributions of the two empty states marked in green and blue color in (b). The red balls represent the oxygen atoms, and the copper atom at the center of tetrahedron is embedded in the isosurface.