Fermi-linearization scheme for itinerant electrons with Clifford   variables
  We propose here an alternative interpretation of the fermi-linarization approach to interacting electron systems, based on the requirement that the coefficients of the linearized operators are Clifford-like variables, whose anticommutator equals an unknown constant $c$. We apply the approximation to the Falicov-Kimball model, explicitly solving the self-consistency equation for the unknown, which turns out to behave as an order parameter. We discuss its relation with a metal-insulator transition and some thermodynamical quantities. In particular we show that our approximation in the $T=0$ limit reproduces exactly the Gutzwiller results for the Hubbard model. 
Arianna Montorsi and Alessandro Pelizzola