Phase diagram, energy scales, and nonlocal correlations in the Anderson lattice model

We study the Anderson lattice model with one f orbital per lattice site as the simplest model which describes generic features of heavy fermion materials. The resistivity and magnetic susceptibility results obtained within dynamical mean-field theory (DMFT) for a nearly half-filled conduction band show the existence of a single energy scale T* which is similar to the single-ion Kondo temperature T-K(o). To determine the importance of intersite correlations, we have also solved the model within cellular DMFT (CDMFT) with two sites in a unit cell. The antiferromagnetic region on the phase diagram is much narrower than in the single-site solution, having a smaller critical hybridization V-c and Neel temperature T-N. At temperatures above T-N the nonlocal correlations are small, and the DMFT paramagnetic solution is in this case practically exact, which justifies the ab initio local density approximation (LDA) + DMFT approach in theoretical studies of heavy fermions. Strong intersite correlations in the CDMFT solution for T < T-N, however, indicate that they have to be properly treated in order to unravel the physical properties near the quantum critical point.