“Ab Initio” Calculation of the Quadrupole Coupling Constant of 14N in HCN, FCN, ClCN, HC2CN, CN−, OCN−, SCN− and the Examination of the Townes–Dailey Interpretation in Terms of Exclusive Orbitals

The electric field gradient at ¹⁴N nucleus in some RCN molecules or RCN⁻ ions has been calculated using the accurate SCF wavefunctions obtained by McLean and Yoshimine. From these computed values and the experimentally known ¹⁴N quadrupole coupling constant of four molecules of this series, a value of ${\text{1.66e\hspace{0.17em}×\hspace{0.17em}10}}^{\text{−26}}{\mathrm{cm}}^2$ for the quadrupole moment of ¹⁴N nucleus has been estimated. A check for the semi‐empirical interpretative theory of Townes and Dailey is made in terms of localized orbitals (Boys exclusive orbitals). Some other characteristics of these exclusive orbitals are also displayed.