  The interaction of two resonant impurities in graphene has been predicted to
have a long-range character with weaker repulsion when the two adatoms reside
on the same sublattice and stronger attraction when they are on different
sublattices. We reveal that this attraction results from a single energy level.
This opens up a possibility of controlling the sign of the impurity interaction
via the adjustment of the chemical potential. For many randomly distributed
impurities (adatoms or vacancies) this may offer a way to achieve a controlled
transition from aggregation to dispersion.
