Friedel oscillations in the one-dimensional Kondo-lattice model
  The paramagnetic metallic phase of the one-dimensional Kondo lattice model is studied by the density-matrix renormalization- group method. We observe charge and spin Friedel oscillations. They reflect the long range charge-charge and spin-spin correlation functions. The observed oscillations are consistent with a Tomonaga-Luttinger liquid. From the period of the oscillations it is concluded that the Fermi surface is large, including both the conduction electrons and the localized spins, $k_F=\pi (1+n_c)/2$, where $n_c$ is the density of conduction electrons. 
N. Shibata, K. Ueda, T. Nishino, and C. Ishii