Spin in Density-Functional Theory

Abstract

The accurate description of open-shell molecules, in particular of transition metal complexes and clusters, is still an important challenge for quantum chemistry. While density-functional theory (DFT) is widely applied in this area, the sometimes severe limitations of its currently available approximate realizations often preclude its application as a predictive theory. Here, we review the foundations of DFT applied to open-shell systems, both within the nonrelativistic and the relativistic framework. In particular, we provide an in-depth discussion of the exact theory, with a focus on the role of the spin density and possibilities for targeting specific spin states. It turns out that different options exist for setting up Kohn-Sham DFT schemes for open-shell systems, which imply different definitions of the exchange-correlation energy functional and lead to different exact conditions on this functional. Finally, we suggest some possible directions for future developments.

References in corpus (7)

• Fractional spins and static correlation error in density functional theory
• Nonuniqueness of the Potentials of Spin-Density-Functional Theory
• Density Functional Theory of Magnetic Systems Revisited
• Accurate ab initio spin densities
• The many-electron ground-state determines uniquely the potential in Spin-Density-Functional Theory for non-collinear magnetism
• On the thermodynamical analogy in spin-polarized density functional theory
• Derivative of the Lieb definition for the energy functional of density functional theory with respect to the particle number and the spin number

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