ON CHF CALCULATIONS OF 2ND-ORDER MAGNETIC-PROPERTIES USING THE METHODOF CONTINUOUS TRANSFORMATION OF ORIGIN OF THE CURRENT-DENSITY

A fully analytical formulation is outlined for computing molecular mag netic susceptibilities and nuclear magnetic shieldings via a continuou s change of origin of the electronic current density induced by an ext ernal magnetic field. The change of origin is described in terms of a (continuous) arbitrary shift function d(r). Coupled Hartree-Fock secon d-order magnetic properties of CH4 and CO2 molecules have been compute d, using the special choice d(r) = r as generating function. A detaile d analysis of results obtained with a variety of basis sets reveals th at such a method is not as good as previously suggested. Large basis s ets must be used to obtain accurate magnetic properties. On the other hand, all the components of theoretical nuclear magnetic shielding eva luated via this approach are independent of the origin of the vector p otential. In general, theoretical magnetic susceptibilities depend lin early on the distance between different coordinate frames, but are ori gin independent for centre-symmetric molecules.