Theory of magnetic susceptibilities and N.M.R. chemical shifts in terms of localized quantities

A method based on Individual Gauge for Localized (molecular) Orbitals (IGLO) proposed recently has been applied to a study of the magnetic susceptibilities and the chemical N.M.R. shifts of the molecules N₂, HCN, CO, C₂H₂, CO₂, N₂O, O₃, FNO and OF₂. Large basis sets have been used and the results are presumed to be close to the Hartree-Fock limit. The agreement with experiment is fair as far as reliable experimental data are available (both for the isotropic shifts and the anisotropies), although it seems that the present calculations overestimate somewhat the paramagnetic contributions. Possibly correlation effects, neglected so far, play a rôle here. Ozone is a quite exceptional molecule in several respects; it is van Vleck paramagnetic, there is extreme antishielding of the nuclei and the dependence of both χ and σ on small changes of the geometry is fantastic.