HARTREE-FOCK LIMIT MAGNETIZABILITIES FROM LONDON ORBITALS

Molecular magnetizabilities have been calculated at the Hartree-Fock l evel for a series of diamagnetic molecules: H2O, NH3, CH4, PH3, H2S, C O2, CSO, CS2, and C3H4. Gauge invariance is imposed by the use of Lond on atomic orbitals. The results are compared to those obtained with th e IGLO (individual gauge for localized orbitals) method and are found to converge faster to the basis set limit. Magnetizabilities obtained from basis sets of different quality never differ by more than 4% for the London method, compared to 20% for IGLO. The Hartree-Fock limit ma y be approached using London basis sets of moderate size, in contrast to calculations of molecular polarizabilities which require large basi s sets to be reliable. Comparison with experiment shows that the Hartr ee-Fock method overestimates experimental susceptibilities by 5%-10%.