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The half filled Hubbard model is studied in the pair approximation of theCluster Variation Method. The use of the $SO(4)$ symmetry of the model makespossible to give a complete analytical characterization of the ground state, bymeans of explicit expressions for the double occupancy and the nearest neighborcorrelation functions. The finite temperature analysis is reduced to thenumerical solution of only two coupled transcendental equations. The behaviorof local magnetic moment, specific heat and correlation functions is given forsome typical cases in one and two dimensions. We obtain good qualitativeagreement with exact and numerical results in one dimension. The results forfinite temperatures show a rapid evolution, with increasing temperature, from astrongly antiferromagnetic behavior to a disordered one; in the hightemperature region a maximum (which has been related to a "gradual"metal--insulator transition) is found in the specific heat for very largevalues of the Coulomb repulsion.Comment: 14 pages, 7 figures (appended as PostScript files

The half-filled Hubbard model in the pair approximation of the cluster variation method