Density functional study of K and Na adsorbed on Co(0001)
College of Physics and Information Engineering, Henan Normal University, Xinxiang, Henan, 453007, P.R. China
Corresponding author: a email@example.com
Revised: 26 April 2010
Published online: 4 June 2010
The adsorption of alkali atom K and Na on Co(0001) in p(2×2) and ( × )R30° phases were studied by periodic density functional theory calculations. It was shown that K and Na adsorption in hollow, bridge and top sites are practically degenerate for the two phases. Optimized geometries for p(2×2)-K and predicted decrease of the work function induced by K are in good agreement with experiments. And our calculations are consistent with the general adsorption picture in comparison with other systems. Detailed analysis of the electronic structures indicates that the decrease of work function upon the adsorption of K and Na can be attributed to the dipole moment associated with the positively polarized alkali atom, which is characterized by the charge depletion from alkali layer and charge accumulation in the interface region. The bonding of K and Na with Co(0001) surface is found to have a metallic bond of covalent character at both 0.25 and 0.33 ML.
© EDP Sciences, Società Italiana di Fisica, Springer-Verlag, 2010