Layer- and orbital-resolved DFT calculations of Fe(001)–p(1 × 1)-O (a) near EF along the Γ¯–X¯ high symmetry line of the surface Brillouin zone. (a)–(c) Fe dxy, (d)–(f) Fe dyz, and (g) O py. S and S-1 denote the topmost and second Fe layers for the d orbitals.