  We investigate the mutual influence of impurities in two-dimensional d-wave
superconductors involving self-consistent solutions of the Bogoliubov-de Gennes
equations. The local order parameter suppression, the local density of states
(LDOS) as well as the interference of impurity-induced structures are analyzed.
We employ an impurity position averaging scheme for the DOS that does not
neglect these interference effects, as the commonly used $T$-matrix approaches
do.
