What about MPI? Running SWIFT on more than one node

After compilation, you will be left with two binaries. One is called swift, and the other swift_mpi. Current wisdom is to run swift if you are only using one node (i.e. without any interconnect), and one MPI rank per NUMA region using swift_mpi for anything larger. You will need some GADGET-2 HDF5 initial conditions to run SWIFT, as well as a compatible yaml parameter file.