  The half-filled extended Hubbard model, in one and two dimensions, is studied
by means of the 2-pole approximation within the Composite Operator Method with
the aim at improving the possibilities to describe some of the experimental
features observed for quasi-1D organic superconductors and Cu-O planes of
cuprates. The phase diagrams ($T$-$V$ and $V$-$U$) are analyzed with respect to
the paramagnetic metal - paramagnetic insulator - charge ordered phase
transitions. The relevant features of the diagrams (rank of the phase
transitions, critical points, reentrant behavior) are discussed in detail.
