How Well Can Kohn-Sham DFT Describe the HO2 + O3 Reaction?

In a previous work (J. Chem. Theory Comput. 2010, 6, 412) we reported an ab initio investigation of the reaction between ozone and the hydroperoxyl radical. The studies on this atmospheric reaction are here continued with an evaluation of different exchange-correlation functionals (all rungs of "Jacob's ladder" of density functional approximations are represented) in Kohn-Sham DFT calculations. We focus on the comparison between the barrier heights of the oxygen- and hydrogen-abstraction mechanisms here calculated with the ones previously obtained at the CASPT2(11,11)/AVTZ level. The comparison is also extended to the remaining stationary points. Additionally, a relation between the fraction of exact exchange of one-parameter hybrid functionals and the imaginary frequency of a saddle point is developed, originating three new functionals that are also used in the present benchmark calculations.