and product complexes (PCi). iv) Both channels are very exothermic and consequently, low barrier heights are expected, which appear close to the reactants, i.e., "early" on the reaction paths. v) Both paths present heavy-light-heavy mass combinations (HLH). As a consequence of this kinematic condition substantial vibrational excitation would be expected, especially in the triatomic product, water molecule. Finally, vi) The H2O(v) vibrational distribution has been reanalysed in recent years, due to experimental difficulties. Given the scarce dynamics information and the experimental revisions on the H2O(v1,v2,v3) vibrational populations, v1, v2 and v3 being, respectively, the symmetric stretching, the bending and the antisymmetric stretching modes of water, the main aims of the present work are two-fold: first, to develop for the first time an analytical fulldimensional PES (potential energy surface) describing the nuclei motions; and second, based on this surface, to perform a theoretical dynamics analysis to simulate the experimental evidence on the H2O(v1,v2,v3) vibrational distribution at room temperature.