SPECTRAL-WEIGHT TRANSFER - BREAKDOWN OF LOW-ENERGY-SCALE SUM-RULES INCORRELATED SYSTEMS

In this paper we study the spectral-weight transfer from the high- to the low-energy scale by means of exact diagonalization of finite clust ers for the Mott-Hubbard and charge-transfer model. We find that the s pectral-weight transfer is very sensitive to the hybridization strengt h as well as to the amount of doping. This implies that the effective number of low-energy degrees of freedom is a function of the hybridiza tion and therefore of the volume and temperature. In this sense it is not possible to define a Hamiltonian which describes the low-energy-sc ale physics unless one accepts an effective nonparticle conservation.