Calculation of electric dipole hypershielding at the nuclei in diatomic molecules

The third-rank electric hypershielding at the nuclei of eight diatomic molecules and carbon dioxide has beenevaluated at the Hartree–Fock level of accuracy (i) by straightforward use of its definition within the Rayleigh–Schr€odinger perturbation theory and (ii) by a pointwise procedure for geometrical derivatives of electric dipole polarizability.The connection between these quantities is provided by the Hellmann–Feynman theorem. Extended ad hocbasis sets of big size and high flexibility have been employed in a numerical test of the theory to assess its practicality. Itis shown that constraints for rototranslational invariance and conditions provided by the virial theorem yield a naturalcriterion for near Hartree–Fock quality of nuclear electric hypershieldings computed by procedure (i).