THE PERIODIC ANDERSON MODEL IN THE GENERATING FUNCTIONAL APPROACH

摘要

The periodic Anderson model at arbitrary values of the on-site Coulomb repulsion is studied by the generating functional approach. For the Green's function of the localized d-electrons an exact equation is derived with variational derivatives with respect to fluctuating fields. It coincides with the one for the Hubbard model if the hopping matrix element t_(ij) is replaced by the effective one Δ_(ij)(ω), that depends on frequency and is proportional to the hybridization parameter squared. It is shown that the first-order correction with respect to Δ_(ij)(ω) for the terminal part of the Green's function contains a singular term originating from the interaction of d-electrons with spin fluctuations. The dynamical susceptibility of these fluctuations is calculated in the hydrodynamic limit.