n> <span class="n">np</span><span class="o">.</span><span class="n">ndarray</span><span class="p">:</span>
    <span class="sa">r</span><span class="sd">&quot;&quot;&quot;</span>
<span class="sd">    Compute the Hamiltonian from the kinetic and potential terms.</span>

<span class="sd">    | Args:</span>
<span class="sd">    |     s: iDEA.system.System, System object.</span>
<span class="sd">    |     up_n: np.ndarray, Charge density of up electrons.</span>
<span class="sd">    |     down_n: np.ndarray, Cha