Quadrupole moment of CO, N2, and NO/+/

Evaluation of quadrupole moments obtained for CO, N2, and NO(+) with multiconfiguration self-consistent-field wave functions chosen by the optimized valence configuration (OVC) approach of Wahl and Das (1972). The quadrupole moments thus obtained are compared with both experimental and Hartree-Fock values. The Hartree-Fock results are found to be not very accurate for N2, especially if vibrational averages over vibrational levels greater than 1 or 2 are to be taken. The agreement between the OVC quadrupole moment and the experimental values is found to be best for CO.