Relativistic and electron-correlation effects on magnetizabilities investigated by the Douglas-Kroll-Hess method and the second-order Møller-Plesset perturbation theory.

Isotropic and anisotropic magnetizabilities for noble gas atoms and a series of singlet and triplet molecules were calculated using the second-order Douglas-Kroll-Hess (DKH2) Hamiltonian containing the vector potential A and in part using second-order generalized unrestricted Møller-Plesset (GUMP2) theory. The DKH2 Hamiltonian was resolved into three parts (spin-free terms, spin-dependent terms, and magnetic perturbation terms), and the magnetizabilities were decomposed into diamagnetic and paramagnetic terms to investigate the relativistic and electron-correlation effects in detail. For Ne, Kr, and Xe, the calculated magnetizabilities approached the experimental values, once relativistic and electron-correlation effects were included. For the IF molecule, the magnetizability was strongly affected by the spin-orbit interaction, and the total relativistic contribution amounted to 22%. For group 17, 16, 15, and 14 hydrides, the calculated relativistic effects were small (less than 3%), and trends were observed in relativistic and electron-correlation effects across groups and periods. The magnetizability anisotropies of triplet molecules were generally larger than those of similar singlet molecules. The so-called relativistic-correlation interference for the magnetizabilities computed using the relativistic GUMP2 method can be neglected for the molecules evaluated, with exception of triplet SbH. Copyright 2009 Wiley Periodicals, Inc.