A flexible method to evolve collisional systems and their tidal debris
  in external potentials
  We introduce a numerical method to integrate tidal effects on collisional
systems, using any definition of the external potential as a function of space
and time. Rather than using a linearisation of the tidal field, this new method
follows a differential technique to numerically evaluate the tidal acceleration
and its time derivative. Theses are then used to integrate the motions of the
components of the collisional systems, like stars in star clusters, using a
predictor-corrector scheme. The versatility of this approach allows the study
of star clusters, including their tidal tails, in complex, multi-components,
time-evolving external potentials. The method is implemented in the code nbody6
(Aarseth 2003).
