The experimental ARPES image plot and of Fe(001)–p(1 × 1)-O (a) near E_F along the Γ¯ –M¯ high symmetry line of the surface Brillouin zone taken at hν = 55 eV with the s-polarization geometry. DFT calculation results of the Fe d_{x² − y²} orbital component for (b) the topmost (S), (c) second (S-1), and (d) bulk Fe layers. The dashed lines in (a) are guides for the band dispersions.