Documentation: add submission script on Perlmutter

doc/source/user_guide/installation_perlmutter.rst

@@ -19,13 +19,42 @@ environment, in which to install `optimas`.
 
     python3 -m pip install optimas
 
-Running
-~~~~~~~
+Running an optimas job
+~~~~~~~~~~~~~~~~~~~~~~
 
-Before using `optimas`, execute the following commands to activate
-the virtual environment:
+In order to run a new optimas job, create a new folder in the ``$SCRATCH``
+directory, and add the files needed to describe your optimization, i.e. typically:
+
+* a file ``run_optimization.py``
+* a template simulation input script
+* a file ``analysis_script.py`` that postprocesses the simulation results
+
+(See a typical example `here <https://github.com/optimas-org/optimas/tree/main/examples/ionization_injection>`_.)
+
+Then, create a file ``submission_script`` with the following content:
 
 ::
 
+    #!/bin/bash -l
+    #SBATCH -t <walltime>
+    #SBATCH -N <n_nodes>
+    #SBATCH -A <nersc_account>
+    #SBATCH -C gpu
+    #SBATCH -q regular
+    #SBATCH --exclusive
+    #SBATCH --gpu-bind=none
+    #SBATCH --gpus-per-node=4
+
     module load cray-python/3.9.13.1
     source $HOME/sw/perlmutter/gpu/venvs/optimas/bin/activate
+
+    python run_optimization.py
+
+where ``<walltime>``, ``<n_nodes>`` and ``<nersc_account>`` should be replaced
+by the wall time, number of nodes and NERSC account number that you want to use.
+
+Then run:
+
+::
+
+    sbatch submission_script