Interactions between a massive planet and a disc
  We analyse the potential migration of massive planets forming far away from
an inner planetary system. For this, we follow the dynamical evolution of the
orbital elements of a massive planet undergoing a dissipative process with a
gas disc centred around the central sun. We use a new method for
post-Newtonian, high-precision integration of planetary systems containing a
central sun by splitting the forces on a particle between a dominant central
force and additional perturbations. In this treatment, which allows us to
integrate with a very high-accuracy close encounters, all gravitational forces
are integrated directly, without resorting to any simplifying approach. After
traversing the disc a number of times, the planet is finally trapped into the
disc with a non-negligible eccentricity
