  With quantum Monte Carlo methods, we investigate the consequences of placing
a magnetic adatom adjacent to a vacancy in a graphene sheet. We find that
instead of the adatom properties depending on the energy of the adatom orbital,
as in a single impurity problem, they develop a dependence on the energy of the
split localized state associated with the single vacancy problem. Shifting the
chemical potential through this experimentally more accessible energy scale
reveals novel behavior in the spectral density, magnetic susceptibility, and
the correlations of the adatom spin and charge with those of the conduction
electrons. In general, the behavior of the adatom in the presence of a vacancy
differs significantly from its behavior in the absence of a vacancy.
