n><span class="n">a</span><span class="p">]</span> <span class="k">for</span> <span class="n">a</span> <span class="ow">in</span> <span class="n">group</span><span class="p">]</span>
            <span class="n">species</span> <span class="o">=</span> <span class="p">[</span><span class="n">a</span><span class="o">.</span><span class="n">specie</span> <span class="k">for</span> <span class="n">a</span> <span class="ow">in</span> <span class="n">atoms</span><span class="p">]</span>
            <span class="n"