Potential energy surface of H₂O⁺: linear approach

An SCF+CI calculation of the potential energy surface of H 2 O + in C infinity v symmetry (linear approach) is reported. No energy barrier has been found for the chemical reaction O + +H 2 to OH + +H. Instead, the energy of the intermediate species (O...H...H) + is found to be 12 kcal/mole below the energy of the input products. This leads to the conclusions that the reaction can actually occur at low temperatures (interstellar clouds) and that the complete potential energy surface is worth computing.