_atoms</span> <span class="o">=</span> <span class="nb">len</span><span class="p">(</span><span class="n">struct</span><span class="o">.</span><span class="n">species</span><span class="p">)</span>
    <span class="n">fc</span> <span class="o">=</span> <span class="n">np</span><span class="o">.</span><span class="n">array</span><span class="p">(</span><span class="n">struct</span><span class="o">.</span><span class="n">frac_coords</span><span class="p">)</span>
    <span class="n">fc_copy</span> <span class