Ab initio potential functions for the ionic states of OH

Abstract Potential curves of the OH molecule correlating to the four lowest energy dissociation limits O ( 3 P )+ H ( 2 S ), O ( 1 D )+ H ( 2 S ), O ( 1 S ) + H ( 2 S ), O − ( 2 P ) + H + have been computed at the CI/CASSCF level with the AUG-cc-pVTZ basis sets with a special emphasis on the ion-pair states 3 2 Π and C 2 Σ + . A balanced treatment of the excited state potentials is achieved by using the state-averaging MO optimization procedure. The X 1 Σ + and 1 Π potentials of OH − have been also considered. After empirical correction of the errors at the dissociation limits, the computed functions are recommended for the future use in the diatomics-in-molecules studies of the structure and dynamics of oxygen/hydrogen containing molecular systems.