For the nominal LHC parameters the coherent beam-beam pi-mode is outside the incoherent continuum and therefore does not experience Landau damping. Mechanisms to restore damping by reducing the degree of symmetry between the two beams are effective, but may not be desirable due to possible side effects. Since the synchrotron tune and the linear beam-beam tuneshift have the same order of magnitude for the LHC, Landau damping could be provided by overlapping the discrete modes with the synchrotron sidebands of the incoherent continuum. The presence of a crossing angle between the colliding beams can excite such synchrotron sidebands. To simulate this effect, an earlier program using a Hybrid Fast Multipole Method was adapted and longitudinal motion was included. The longitudinal-transverse coupling due to the crossing angle is modelled by longitudinal slicing of the bunches. To improve the execution speed, the program is designed to run on a parallel cluster of machines, using the MPI protocol.
