La₂CuO₄ bands

Electronic energy-band structure of the classical high-temperature superconductor La2CuO4, calculated with the LMTO method and using the LDA. The 'fatness' shown in red is a measure of the Cu d(x2-y2)orbital character. That this character appears not only in the conduction band, but also in the dispersionless band near -2 eV, is due to hybridization with the Cu d(3z2-1) and apical-oxygen pz orbitals. This feature is absent in most other cuprate high-temperature superconductors.