First at all, MPI must be installed on your running machine.

1/ Then compile with the "key_MPI_2D" CPP key and set "FC = mpiifort" in your Makefile.caparmor.
2/ Prepare your "mpi.txt" file (see mars_decoupe_manual on internet website)
3/ run tho code with the command runmpi_connect

Firstly, since the file must be a netCDF file, define l_bathy_save=.true. in your paraspec.txt, run the code a few seconds, and it will save the bathymetry (H0,HX,HY) into the file. This bathymetry is the one you use throughout the simulation.
Secondly, rename as bathy_[CONF].nc