GENERALIZATIONS OF DMFT, CPA AND NCA

摘要

Local and non-local generalizations of dynamical mean-field theory (DMFT) are presented. They come from a self-avoiding walk in a hypercubic lattice, in which the principle of exclusion and inclusion is used. The coherent potential approximation (CPA) can be treated in a similar way. CPA and DMFT can be mapped onto each other. The numerical corrections to the DMFT are relatively weak, with the non-crossing approximation (NCA) used for the single impurity part. NCA-generalizations similar to those of the Wielfle group are set up with direct self-consistent perturbation theory.