ms is the distance of two closest</span>
<span class="sd">        copies.</span>

<span class="sd">        Returns:</span>
<span class="sd">            np.array: 3D matrix containing the pairwise distance vectors.</span>
<span class="sd">        &quot;&quot;&quot;</span>
        <span class="k">if</span> <span class="bp">self</span><span class="o">.</span><span class="n">_displacement_tensor</span> <span class="ow">is</span> <span class="kc">None</span><span class="p">:</span>

            <span class="n">D