Within Hartree–Fock theory, the ferromagnetic fluid abruptly becomes more stable than the paramagnetic fluid at a density parameter of formula_26 in three dimensions (3D) and formula_27 in two dimensions (2D). However, according to Hartree–Fock theory, Wigner crystallization occurs at formula_28 in 3D and formula_29 in 2D, so that jellium would crystallise before itinerant ferromagnetism occurs. Furthermore, Hartree–Fock theory predicts exotic magnetic behavior, with the paramagnetic fluid being unstable to the formation of a spiral spin-density wave. Unfortunately, Hartree–Fock theory does not include any description of correlation effects, which are energetically important at all but the very highest densities, and so a more accurate level of theory is required to make quantitative statements about the phase diagram of jellium.