ed output (e.g. differently sized systems,</span>
<span class="sd">            different number of centers or different number of included atoms),</span>
<span class="sd">            a regular python list is returned. The dimensions are:</span>
<span class="sd">            [(n_systems,) n_centers, n_atoms, 3, n_features]. The first</span>
<span class="sd">            dimension goes over the different systems in case multiple were</span>
<span class="sd">            given. The second dimension goes over the 