class="reference external" href="https://docs.python.org/3/library/stdtypes.html#str" title="(in Python v3.11)"><em>str</em></a><em>, </em><em>optional</em>) – The MPI command for running LAMMPS in parallel.  If not given, LAMMPS
will run serially.</p></li>
<li><p><strong>sim_directory</strong> (<a class="reference external" href="https://docs.python.org/3/library/stdtypes.html#str" title="(in Python v3.11)"><em>str</em></a><em>, </em><em>optional</em>) – The path to the directory to perform the simulat