  In order to investigate the effects of nonmagnetic impurities in strongly
correlated systems, Quantum Monte Carlo (QMC) simulations have been carried out
for the doped two-dimensional Hubbard model with one nonmagnetic impurity.
Using a bare impurity potential which is onsite and attractive, magnetic and
single-particle properties have been calculated. The QMC results show that
giant oscillations develop in the Knight shift response around the impurity
site due to the short-range antiferromagnetic correlations. These results are
useful for interpreting the NMR data on Li and Zn substituted layered cuprates.
