Abstract
A new formulation of a relativistic current- and spin-density functional theory is proposed. By choosing the charge density and the magnetization density as the two basic variables, a single-particle equation is derived in a form suitable to an isolated atom or ion. The effect of the orbital current is included implicitly through the spin-orbit interaction and explicitly through the Zeeman term in which the spin and the orbital angular momenta couple with an effective magnetic field. The effective magnetic field is given by the variation of the exchange and correlation energy functional with respect to the magnetization density which consists of the spin and the orbital angular momentum density, and should be determined self-consistently. The single-particle equation is applied to an atomic structure calculation for the trivalent ions of the lanthanide series, and the total spin and the orbital angular momenta are found to obey Hund's rules well.
