Accurate global potential energy surface for the H + OH⁺ collision

We mapped the global three-dimensional potential energy surface (3D-PES) of the water cation at the MRCI/aug-cc-pV5Z including the basis set superposition (BSSE) correction. This PES covers the molecular region and the long ranges close to the H + OH⁺(X³Σ⁻), the O + H₂⁺(X²Σ_g⁺), and the hydrogen exchange channels. The quality of the PES is checked after comparison to previous experimental and theoretical results of the spectroscopic constants of H₂O⁺(⁠|$\tilde X$|$X̃$²B₁) and of the diatomic fragments, the vibronic spectrum, the dissociation energy, and the barrier to linearity for H₂O⁺(⁠|$\tilde X$|$X̃$²B₁). Our data nicely approach those measured and computed previously. The long range parts reproduce quite well the diatomic potentials. In whole, a good agreement is found, which validates our 3D-PES.