(color online) Orbital-resolved partial DOS plots for the CO molecule and the surface O and H atoms (top, bridge, and hollow) with the coverage Θ = 0.25: (a), (b) free (dashed line) and adsorbed CO (solid line), and adsorbed kaolinite (001) surface at the top adsorption site; (c), (d) adsorbed CO and adsorbed kaolinite (001) surface at the bridge adsorption site; (e), (f) adsorbed CO and adsorbed kaolinite (001) surface at the hollow adsorption site. The insets show the side view of electron density difference for the CO atoms at the (a) top, (c) bridge, and (e) hollow adsorption sites.