Weak-coupling theory of the periodic Anderson model in infinite dimensions

Second-order perturbation theory is applied to the periodic Anderson model in infinite dimensions. In the particle-hole symmetric case, the electron density of states (DOS) has a hybridization gap at the Fermi level at T=0; the width Δ of the gap decreases as the interaction U increases. It is found that Δ-1 is roughly proportional to the mass enhancement. Furthermore, using this model, we discuss the Van Vleck susceptibility at T=0. The Van Vleck term is found to be enhanced by the interaction in the weak coupling region. ((orig.))