iagonal.</span>
        <span class="k">if</span> <span class="n">np</span><span class="o">.</span><span class="n">any</span><span class="p">(</span><span class="n">system</span><span class="o">.</span><span class="n">get_pbc</span><span class="p">()):</span>
            <span class="n">triu_indices</span> <span class="o">=</span> <span class="n">np</span><span class="o">.</span><span class="n">triu_indices</span><span class="p">(</span><span class="nb">len</span><span class="p">(</span><span class="n">dist