Electronic Structure of the First Excited State of CO. I. SCF Wavefunction Calculated in the Restricted Hartree—Fock Formalism

Abstract

An SCF wavefunction calculated in the restricted Hartree—Fock formalism is reported for the lowest excited state (a ³II) of CO. The expansion method is used and exponents are optimized. Even though the calculated energy and Hellmann—Feynman forces are reasonable, there is a large discrepancy between the calculated and experimental dipole moment. The discrepancy is caused by the fact that the restricted Hartree—Fock function for open‐shell systems does not satisfy Brillouin's theorem and first‐order corrections come in. In particular, it is found that the charge‐transfer states have a large first‐order effect on the dipole moment. Some preliminary results on the isoconfigurational A ¹II state are reported. They indicate that the charge distributions of the two isoconfigurational states are quite different.