Self-consistent electronic band-structure determination of the chemisorption bond length of oxygen on Al(111)

The electronic structure of a five-layer Al(111) film with an adsorbed oxygen overlayer on each side is calculated by the self-consistent linearized augmented plane wave (LAPW) method with dz, the interplanar distance between the oxygen and Al surface plane set equal to 1.33 in accordance with the value given by low-energy electron diffraction measurements. Comparison of the results (work function, position, and dispersion of the O 2p bands) with our earlier self-consistent LAPW results obtained with dz=0.70 [the extended x-ray absorption fine-structure (EXAFS) value] and with experiment shows that a definite choice can be made of the correct geometry for the chemisorption phase. We find better agreement when the EXAFS value of dz is used and conclude that the length of the chemisorption bond distance, OAl, on Al(111) is 1.79 as given by the EXAFS experiment.