HARTREE-FOCK LIMIT MAGNETIZABILITIES FROM LONDON ORBITALS

Molecular magnetizabilities have been calculated at the Hartree-Fock level for a series of diamagnetic molecules: H2O, NH3, CH4, PH3, H2S, CO2, CSO, CS2, and C3H4. Gauge invariance is imposed by the use of London atomic orbitals. The results are compared to those obtained with the 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 may be approached using London basis sets of moderate size, in contrast to calculations of molecular polarizabilities which require large basis sets to be reliable. Comparison with experiment shows that the Hartree-Fock method overestimates experimental susceptibilities by 5%-10%.