Orbital Polarization in Relativistic Density Functional Theory

The description of orbital magnetism by means of modern density functional approaches is considerably less advanced than the evaluation of spin-related magnetic properties. A frequently practiced cure for orbital magnetism are empirical orbital corrections. In the simplest and mostly used version a term proportional to the square of the angular momentum expectation value is added to the exchange and correlation energy for each atom . There is, hitherto, no systematic derivation of the OP corrections from density functional theory. Such a derivation will be given in this book in the framework of the current density functional theory based on the Kohn-Sham-Dirac equation that provides a natural route to orbital magnetism. Related orbital polarization energies of 3d and 4f ions are evaluated.