Compute the Kohn–Sham orbitals nearest the Fermi level (HOMO-1, HOMO, LUMO, LUMO+1, per spin channel) at the Γ point, as signed real wavefunctions. Returns one Gaussian cube with a dataset per state, which Ouro renders with an orbital picker, plus the energies and the gap at Γ in JSON. Degenerate levels are returned whole. Best suited to supercells, slabs, molecules in a box, and defects, where Γ is the natural point; in a small primitive cell the band edges may lie elsewhere in the zone.