The prediction of nuclear quadrupole moments from a b i n i t i o quantum chemical studies on small molecules. II. The electric field gradients at the 17O, 35Cl, and 2H nuclei in CO, NO+, OH−, H2O, CH2O, HCl, LiCl, and FCl

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Abstract
The electric field gradients (efg’s) at the oxygen and hydrogen nuclei in CO,NO+, OH−, H2O, and CH2O, and at the chlorine, lithium, and hydrogen nuclei in HCl, LiCl, and FCl, calculated using ab initio quantum chemical methods, are reported. Using extended Gaussian basis sets, the efg’s at the oxygen and chlorine nuclei were computed at the self-consistent field (SCF), singles and doubles configuration interaction [CI(SD)], and coupled pair functional (CPF) levels of theory as the expectation values of the efg operator and also as the energy derivatives of the appropriate perturbed Hamiltonian using the finite field method. The efg’s at the hydrogen and lithium nuclei were computed as expectation values. Corrections due to zero point vibrational motions were also calculated. The effect of basis set incompleteness on the calculated efg’s is discussed and, where possible, corrected for. The calculated efg’s, together with the experimental nuclear quadrupole coupling constants, are used to estimate the 17O, 35Cl, and 2H nuclear quadrupole moments, and to test the quality of the correlated wave functions generated by the CI(SD) and CPF methods. The recommended values on the basis of the present calculations are −2.64±0.03, −8.2±0.2, and 0.278 fm2, respectively, for the 17O, 35Cl, and 2H nuclear quadrupole moments.