Scattering theory and ground-state energy of Dirac fermions in graphene with two Coulomb impurities Denis Klöpfer, Alessandro De Martino, Davron U. Matrasulov and Reinhold Egger Eur. Phys. J. B, 87 8 (2014) 187 Published online: 11 August 2014 DOI: 10.1140/epjb/e2014-50414-8