Numerical package for QFT calculations of defect-induced phenomena in graphene

We introduce a computationally efficient method based on the path integral formalism to describe defect-modified graphene. By taking into account the entire Brillouin zone, our approach respects the lattice symmetry and can be used to investigate both short-range and long-range effects. The proposed method's key advantage is that the computational complexity does not increase with the system size, scaling, instead, with the number of defects. As a demonstration of our method, we explore the graphene-mediated RKKY interaction between multiple magnetic impurities. Our results concur with earlier findings by showing that the interaction strength and sign depend on various factors like impurity separation, sublattice arrangement, and system doping. We demonstrate that frustration can be introduced between the impurity spins by controlling their relative positions and that this frustration can be switched on and off by tuning the chemical potential of the system.