Charge-transfer effects in oxygen chemisorption on nickel (001)

Calculations of the electron density in oxygen overlayers on a nickel (001) surface show a ‘‘ball-and-stick’’ model to be inappropriate in understanding the small work-function increase measured on chemisorption. The form of the charge transfer and the effective surface dipole layer is explained in terms of the very large 2p-like oxygen orbitals that span the O 2p–like bands.