A full dimensional quantum dynamics calculation has been carried out to study the prototypical complex forming H + CO2 -> OH + CO reaction. The total reaction probability is converged with a propagation time much shorter than the reverse reaction, and only exhibits very small oscillatory structures, indicating the reaction proceeds mainly through a direct mechanism. The strong Fermi resonance between the (020) and (100) vibrationally excited states makes it hard to define their efficacy for reactivity, although it is conceivable that the bending excitation is much more effective than the symmetric excitation according to the geometry of the transition state in the entrance channel. (C) 2017 Elsevier B.V. All rights reserved.