Semi-major axis a, and the heliocentric distance r versus time t for the simulation Sigma_3times. The convergence radius is shifted further out to 11 au. Merging seems more difficult in this case as there are many “repulsions”, especially between embryos 3 and 4. The black arrow indicates the repulsion event we study in detail. The semi-major axis is systematically offset from the radial distance, a > r, because the orbits are substantially non-Keplerian. After approximately t ≐ 10 000 P_orb some unwanted interaction with the disc edge occurs and the evolution is no longer reliable. The masses reach 5–7 M_⊕ prior to this.