  A most basic and puzzling enigma in surface science is the description of the
dissociative adsorption of O2 at the (111) surface of Al. Already for the
sticking curve alone, the disagreement between experiment and results of
state-of-the-art first-principles calculations can hardly be more dramatic. In
this paper we show that this is caused by hitherto unaccounted spin selection
rules, which give rise to a highly non-adiabatic behavior in the O2/Al(111)
interaction. We also discuss problems caused by the insufficient accuracy of
present-day exchange-correlation functionals.
