Excited states of gaseous ions. IV. Potential energy surfaces of the H2O+ ion

Cross-sections of the potential energy hypersurfaces are reported for the four lower-lying states of the H₂O⁺ molecular ion. The symmetric dissociation of the ion has been investigated using the CNDO/2 method supplemented by a configuration interaction calculation. Self-consistent-field wave functions were calculated for the asymmetric dissociation using an extended basis of Gaussian-lobe functions. The values of the hydrogen exponents are found to be very sensitive to the molecular geometry. The calculated equilibrium H-O-H angle is 123° in the X?²B₁ state, nearly 180° in the X?A²A₁ state and 69° in the B?²B₂ state. The lower-lying quartet á ⁴B₁ is line entirely repulsive. The potential energy surface of the à ²A₁ state has a peculiar shape, characterized by two dissociation valleys.