  Interaction between adsorbed atoms in graphene is studied using a combination
of DFT and the path integral formalism. Our results reveal a complex
non-monotonic interaction profile. We show that the strength and sign of the
interaction are dictated by the arrangement of impurities, as well as the
system doping. These findings can be used to interpret the complex behavior of
impurities in experimentally realized systems, as well as other classes of
impurities, such as C substitutions in graphene.
