Overhauser’s spin-density wave in exact-exchange spin-density functional theory

Physical Review B 80, 125120 (2009)

Overhauser’s spin-density wave in exact-exchange spin-density functional theory

S. Kurth, F.G. Eich

The spin-density wave ͑SDW͒ state of the uniform electron gas is investigated in the exact-exchange approximation of noncollinear spin-density functional theory ͑DFT͒. Unlike in Hartree-Fock theory, where the uniform paramagnetic state of the electron gas is unstable against formation of the spin-density wave for all densities, in exact-exchange spin DFT this instability occurs only for densities lower than a critical value. It is also shown that, although in a suitable density range it is possible to find a noninteracting SDW ground-state Slater determinant with energy lower than the corresponding paramagnetic state, this Slater determinant is not a self-consistent solution of the optimized effective potential ͑OEP͒ integral equations of noncollinear spin DFT. A self-consistent solution of the OEP equations which gives an even lower energy can be found using an excited-state Slater determinant where only orbitals with single-particle energies in the lower of two bands are occupied while orbitals in the second band remain unoccupied even if their energies are below the Fermi energy.

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