W. Ziegler et al., T-MATRIX FORMULATION OF IMPURITY SCATTERING IN CORRELATED SYSTEMS, Physical review. B, Condensed matter, 53(13), 1996, pp. 8704-8707
Using a generalized T-matrix description which, in principle, exactly
includes Coulomb correlations and potential scattering events, resonan
t and bound impurity states are discussed. Like in the noninteracting
case, the effects of the scattering potential can be divided into diff
erent partial-wave channels, exploiting the symmetry of the underlying
lattice. Due to Coulomb correlations, bare local (i.e., s-wave) poten
tials become dynamic and extended, being responsible also for p-, d-wa
ve, etc., scattering effects. Numerically exact results for both the t
wo-dimensional t-J and Hubbard models are used to construct a simple (
static) approximation to the effective impurity potential which is sho
wn to reproduce the exact resonant scattering and bound states in the
relevant symmetry channels.