ALTERNATIVE TO GUTZWILLERS APPROACH

An efficient variational procedure to calculate the ground-state prope rties of the particle-hole symmetric periodic Anderson model is presen ted. Expectation values are calculated by using an approximate scheme. It is shown that the ground-state energy calculated with the one-site approximation, which essentially is a single-site mean-field approxim ation, is identical to the corresponding energy obtained by the well-k nown Gutzwiller wave function using the Gutzwiller approximation. The two-site approximation, in which intersite correlations are explicitly included, is shown to be a better approximation than the Gutzwiller a pproximation.