  The non-collinear spin-spiral density wave of the uniform electron gas is
studied in the framework of Reduced-Density-Matrix-Functional Theory. For the
Hartree-Fock approximation, which can be obtained as a limiting case of
Reduced-Density-Matrix-Functional Theory, Overhauser showed a long time ago
that the paramagnetic state of the electron gas is unstable with respect to the
formation of charge or spin density waves. Here we not only present a detailed
numerical investigation of the spin-spiral density wave in the Hartree-Fock
approximation but also investigate the effects of correlations on the
spin-spiral density wave instability by means of a recently proposed
density-matrix functional.
