Additional energy contributions are the effective nuclear repulsion E rep 0 and London dispersion E disp n . The short-ranged nuclear repulsion function parameterizes the combination of nuclear-nuclear repulsion E nn , the nuclear-electron attraction of the atomic densities V ext [ρ 0 ], and Coulomb repulsion of the atomic densities J[ρ 0 ]. The final GFN2-xTB energy is given as,