Charge and spin dynamics of the Hubbard chains

We calculate the local correlation functions of charge and spin for the one -chain and two-chain Hubbard model using the density matrix renormalization group method and the recursion technique. Keeping only finite number of st ates we get good accuracy for the low energy excitations. We study the char ge and spin gaps, bandwidths and weights of the spectra for various values of the on-site Coulomb interaction U and the electron filling. In the low e nergy part, the local correlation functions are different for the charge an d spin The bandwidths are proportional to t for the charge and I for the sp in, respectively. (C) 1999 Elsevier Science B.V. All rights reserved.