Scattering theory and ground-state energy of Dirac fermions in graphene   with two Coulomb impurities
  We study the physics of Dirac fermions in a gapped graphene monolayer containing two Coulomb impurities. For the case of equal impurity charges, we discuss the ground-state energy using the linear combination of atomic orbitals (LCAO) approach. For opposite charges of the Coulomb centers, an electric dipole potential results at large distances. We provide a nonperturbative analysis of the corresponding low-energy scattering problem. 
D. Kl\"opfer, A. De Martino, D. Matrasulov, R. Egger
cond-mat.mes-hall