THEORETICAL-STUDY OF LOW-LYING ELECTRONIC STATES OF COH

Potential energy curves and spectroscopic parameters of several electronic states of CoH+ have been calculated using multireference configuration interaction methods. The four lowest-lying states X 4Φ, 1 4Σ-, 1 4Π and 1 4Δ lie between 0 and 0.6 eV. The 2 4Π state, with a minimum slightly below 2.0 eV at R = 2.92 a0, exhibits a second minimum (Re = 4.46 a0, Te = 2.14 eV) due to an avoided crossing between the Co+ occupations d8 and d 7s. Such an interaction is also responsible for the shallow minima predicted for the 2 4Δ and 2 4Φ states. Several doublet states of Σ-, Π, Δ, Φ, and Λ character are bound. Except for 1 2Δ, they are expected to exhibit potential barriers along the dissociation path. All bound states have a d 77σ2 configuration (7σ CoH bonding), with the exception of 1 2Δ which is d8-like and has a significant dσ(Co) contribution into the metal-hydrogen bond. The sextet states 1 6Δ, 1 6Π, 1 6Σ -, and 1 6Φ are repulsive due to single occupation of 7σ. The dissociation energy De (X 4Φ) of 2.18 eV is in good agreement with experimental estimates. The ionization potential (IP) X 3Φ (CoH) into X 4Φ(CoH+) (6σ→∞) is calculated to be 7.23 eV, supporting an experimental lower limit of 7.30±0.10 eV for this quantity. The next IPs result from ionization of 3π into 1 4Δ of CoH+ and 1δ into 2 4Π, whereas 7σ ionization is expected to break the CoH bond. © 1990 American Institute of Physics.