  As a possible mechanism of the $\gamma-\alpha$ phase transition in pristine
cerium a change of the electronic density from a disordered state with symmetry
Fm-3m to an ordered state Pa-3 has been proposed. Here we include on-site and
inter- site electron correlations involving one localized 4f-electron and one
conduction 5d-electron per atom. The model is used to calculate the crystal
field of $\gamma$-Ce and the temperature evolution of the mean-field of
$\alpha$-Ce. The formalism can be applied to crystals where quadrupolar
ordering involves several electrons on the same site.
