Quantitative integral cross sections for the H + CO₂ -> OH + CO reaction from a density functional theory-based potential energy surface

The OH + CO → H + CO₂ reaction is important in combustion, atmospheric, and interstellar chemistry. Whereas the direct reaction has been extensively studied both experimentally and theoretically, the reverse reaction has received relatively less attention. Here we carry out a quasiclassical trajectory study of the hyperthermal H + CO₂ → OH + CO reaction on a new interpolated potential energy surface based on the M06-2X density functional. The results reveal for the first time quantitative agreement with experiment for the reaction cross sections in the range of relative translational energies 1.2–2.5 eV. We attribute this excellent agreement to both the quality of the M06-2X energies, which closely reproduce CCSD(T) energies, and to the potential surface construction strategy that emphasizes both the direct and reverse reactions.