Size and dimensionality effect in single-impurity Anderson model

The dimensionality and the size effect on the magnetic properties of the single-impurity symmetric Anderson model in three-, two-, and one-dimensional lattices has been studied using the quantum Monte Carlo method. We have considered clusters with odd number of sites with the impurity placed at the center of the cluster and have employed open boundary conditions. In 3D and 1D lattices, we find that at sufficiently low temperatures, the system can be in either a spin compensated or noncompensated state as the cluster size is reduced. On the other hand, in 2D the system is always in a spin-compensated state independent of the cluster size. These results imply physics beyond that contained in the simplest Kondo model and may explain the discrepancy between two recent experimental results. (C) 1998 American Institute of Physics. [S0021-8979(98)30811-7].