PATH-INTEGRAL TREATMENT FOR LOCALIZED-ELECTRONS IN THE PERIODIC ANDERSON MODEL

The partition function of the periodic Anderson model is presented as the path integral over the variables of ''slow'' localized d-electrons and of ''light'' conduction selectrons With the energy half-bandwidth w. The adiabatic approximation is applied for d-electrons with level E < 0 through the averaging of the thermal distribution over the ''lig ht'' s-electron trajectories. The conditions are deduced for the tempe rature and for the relative positions of s- and d-electron levels, tha t prove this approximation. Temperature minimum of the effective one-p article d-electron energy with the corresponding maximum of their dens ity of states follow for high temperature and the shallow d-level \E\ < w, while the energy shift delta E(T) demonstrates the Kondo-like tem perature logarithm. The Hubbard-like behaviour of d-electrons is found for deep level \E\ > w and low temperatures.