Abstract
We present an extension of the noncrossing approximation (NCA), which is widely used to calculate properties of Anderson impurity models in the limit of infinite Coulomb repulsion to the case of finite U. A self-consistent conserving pseudoparticle representation is derived by symmetrizing the usual NCA diagrams with respect to empty and doubly occupied local states. This requires an infinite summation of skeleton diagrams in the generating functional thus defining the “symmetrized finite- NCA” (SUNCA). We show that within SUNCA the low-energy scale (Kondo temperature) is correctly obtained, in contrast to other simpler approximations discussed in the literature.
- Received 28 May 2001
DOI:https://doi.org/10.1103/PhysRevB.64.155111
©2001 American Physical Society