Methods of continuous translation of the origin of the current density revisited

Approaches to the calculation of magnetizability and nuclear magnetic shieldings in a molecule, based on continuous translation of the origin of the magnetic field-induced electronic current density, are reviewed. The connections among apparently unrelated philosophies (Geertsen propagator methods, Keith-Bader continuous set of gauge transformations, and analytical reformulation by Lazzeretti, Malagoli, and Zanasi) are emphasized, and a unitary theoretical scheme is given.