Specific heat for the periodic Anderson model

We have considered the symmetric periodic Anderson model (PAM). The specific heat has been calculated in the approximation which corresponds to the Nagaoka-type decoupling scheme for the case of single impurity. It starts to have a double peak structure with the increase of Coulomb repulsion U in analogy to the results for single impurity Anderson model. We have found that the width of a gap in the density of states around the Fermi energy decreases with the increase of U and vanishes for infinite value of this parameter.