PERTURBATIONAL APPROACH TO THE ONE PARTICLE PROPERTIES OF THE HUBBARD-MODEL

It is shown that the Hubbard model can be viewed as limiting case of a periodic Anderson model. This relation is used to set up a perturbation theory for the Hubbard model with the transfermatrixelement t as expansion parameter. One particle properties of the three dimensional Hubbard model in the half filled band case for several values of the local Coulomb interaction U calculated with this method are presented. The results give clear hints towards the formation of a gap in the excitation spectrum. The variation of the free energy on the model parameters is found to be in good agreement with expectations. © 1990 Springer-Verlag.