.. _sphx_glr_auto_examples_Solid_State_Physics_plot_P_RPA.py:


RPA Polarization
================

A diagram containing an operator.




.. image:: /auto_examples/Solid_State_Physics/images/sphx_glr_plot_P_RPA_001.png
    :align: center





.. code-block:: python

    import matplotlib.pyplot as plt
    from feynman import Diagram

    # Set up the figure and ax
    fig = plt.figure(figsize=(8,2))
    ax = fig.add_axes([0,0,1,1], frameon=False)

    # It is best to keep the xlim/ylim ratio the same as the figure aspect ratio.
    ax.set_xlim(0, 1)
    ax.set_ylim(0, 0.25)

    y0 = sum(ax.get_ylim()) / 2

    # Initialize diagram with the ax
    D = Diagram(ax)

    # Polarizability operator
    v11 = D.vertex([0.1, y0])
    v12 = D.vertex(v11.xy, dx=0.15)
    P = D.operator([v11, v12], c=1.3)  # c is the excentricity of the patch
    P.text("$P$")

    # Symbols
    D.text(.35, y0, "=", fontsize=30)

    # Propagator lines
    G_style = dict(style='double elliptic',
                   ellipse_excentricity=-1.2, ellipse_spread=.3,
                   arrow=True, arrow_param={'width':0.03})

    v21 = D.vertex([0.45, y0])
    v22 = D.vertex(v21.xy, dx=0.4)

    G1 = D.line(v22, v21, **G_style)
    G2 = D.line(v21, v22, **G_style)

    # Plot and show
    D.plot()
    plt.show()

**Total running time of the script:** ( 0 minutes  0.046 seconds)



.. only :: html

 .. container:: sphx-glr-footer


  .. container:: sphx-glr-download

     :download:`Download Python source code: plot_P_RPA.py <plot_P_RPA.py>`



  .. container:: sphx-glr-download

     :download:`Download Jupyter notebook: plot_P_RPA.ipynb <plot_P_RPA.ipynb>`


.. only:: html

 .. rst-class:: sphx-glr-signature

    `Gallery generated by Sphinx-Gallery <https://sphinx-gallery.readthedocs.io>`_