Figure 2
Illustration: Carin Cain

Figure 2: Ferromagnetism requires that there is an imbalance in the occupancy of spin-up (pink, right-pointing region) and spin-down (left-pointing) orbitals. Experimentally, both the spin-up and spin-down orbitals are filled (left panel) so there is no ferromagnetism. However, LDA calculations (right panel) predict that the conduction band is set so low that it “swallows” the spin-down band, causing spurious charge spilling from the transition metal orbitals into conduction states and a false positive prediction for ferromagnetism.