Hartree-Fock electron gas
= Hartree-Fock electron gas
{c}
A variational single-Slater-determinant treatment of interacting <electrons> and a neutralizing positive background. For uniform plane-wave occupations the direct background and <electron> terms cancel, leaving kinetic and same-spin exchange <energy>. Allowing <spin> <polarization> or spatially modulated orbitals enlarges the variational class.