Ground and low-lying states of FeH⁺ as derived from ab initio self-consistent field and configuration interaction calculations

The electronic states of FeH+ dissociating into Fe+ (6D) and H (2S) have been studied at the restricted open Hartree-Fock (ROHF) and configuration interaction (CI) level of theory, using a pseudopotential approach and considering or not relativistic effects. The ground state appears to be a 5Δ at the ROHF level but inclusion of correlation effects leads to a 5Π ground state. Nevertheless both states exhibit in all cases a near degeneracy. The calculated D0 is about 90% of the experimental value at the CI level whereas ROHF calculations account only for about 25% of the experimental dissociation energy. © 1989 American Institute of Physics.