<source lang="bash">
# Normal
mpirun -np N+1 /usr/local/bin/relax -multi=`'mpi4py'
# In gui
mpirun -np N+1 /usr/local/bin/relax -multi=`'mpi4py' -g
</source>
where N is the number of slaves you have. See the mpirun documentation for details - this is not part of relax. <br>