Semi-major axes and eccentricities of particles scattered by a single Neptune mass planet on a circular orbit at 2 AU around a 1 M_⊙ star, after 10 000 yrs (left-hand panel) and 1 Myr (right-hand panel). The set-up of the simulation is described in Sect. 2.1. Trojan’s of the planet are labelled by red crosses. After 10 000 yrs, only particles within the inner regions of the chaotic zone (Eq. (1) with C = 2, shown by the dashed lines) have been scattered, whilst by 1 Myr, the full zone has been cleared. Particles are scattered onto orbits at constant pericentre (q) or constant apocentre (Q), thus lie between the dotted lines q ~ a_pl and q ~ a_pl − δa_chaos or Q ~ a_pl and Q ~ a_pl + δa_chaos (Q ~ a_pl).