Calculation of the electric hypershielding at the nuclei of molecules in a strong magnetic field

The third-rank electric hypershielding at the nuclei of 14 small molecules has been evaluated at theHartree-Fock level of accuracy, by a pointwise procedure for the geometrical derivatives ofmagnetic susceptibilities and by a straightforward use of its definition within theRayleigh-Schrödinger perturbation theory. The connection between these two quantities is providedby the Hellmann-Feynman theorem. The magnetically induced hypershielding at the nuclei accountsfor distortion of molecular geometry caused by strong magnetic fields and for related changes ofmagnetic susceptibility. In homonuclear diatomics H2, N2, and F2, a field along the bond directionsqueezes the electron cloud toward the center, determining shorter but stronger bond. It is shownthat constraints for rotational and translational invariances and hypervirial theorems provide anatural criterion for Hartree-Fock quality of computed nuclear electric hypershielding.