Molecular Orientation and Surface Site Dependence of the Dissociative   Adsorption of O$_{2}$/Al(111)
  We reproduced the initial sticking probability of O$_{2}$/Al(111) by use of spin-polarized density functional theory and quantum dynamics calculations. We found a large activation barrier when the molecule is dissociatively adsorbed through $abstraction$ on the top site unlike on the hollow and bridge sites. This barrier is sensitive to the molecular orientation and surface site. The vibrational motion of the molecule facilitates the abstraction due to the $late barrier$. Finally, we suggest a possibility on how widely separated oxygen atoms adsorbed on the surface could be realized. 
K. Shimizu, W.A. Di\~no, and H. Kasai
cond-mat.mtrl-sci physics.chem-ph