.. _sphx_glr_auto_examples_Solid_State_Physics_plot_eph.py:


Electron-phonon coupling self-energy
====================================

A diagram containing loopy lines.




.. image:: /auto_examples/Solid_State_Physics/images/sphx_glr_plot_eph_001.png
    :align: center





.. code-block:: python

    from feynman import Diagram
    import matplotlib.pyplot as plt

    fig = plt.figure(figsize=(8,2))
    ax = fig.add_axes([0,0,1,1], frameon=False)

    ax.set_xlim(0, fig.get_size_inches()[0])
    ax.set_ylim(0, fig.get_size_inches()[1])

    # Init D and ax
    D = Diagram(ax)

    D.x0 = 0.2
    D.y0 = sum(D.ax.get_ylim()) * .35

    # Various size
    opwidth = 1.
    linlen = 2.
    txtpad = .8
    wiggle_amplitude=.1

    # Line styles
    Ph_style = dict(style='elliptic loopy', ellipse_spread=.6, xamp=.10, yamp=-.15, nloops=15)
    DW_style = dict(style='circular loopy', circle_radius=.7, xamp=.10, yamp=.15, nloops=18)
    G_style = dict(style='simple', arrow=True, arrow_param={'width':0.15, 'length': .3})

    # Item 1
    v11 = D.vertex([D.x0, D.y0])
    v12 = D.vertex(v11.xy, dx=opwidth)
    Sigma = D.operator([v11, v12])
    Sigma.text("$\Sigma^{ep}$")

    # Symbol
    D.text(v12.x + txtpad, D.y0, "=")

    # Item 3
    v21 = D.vertex([v12.x + 2 * txtpad,  D.y0 - 0.3])
    v22 = D.vertex(v21.xy, dx=linlen)
    G = D.line(v21, v22, **G_style)
    Ph = D.line(v21, v22, **Ph_style)

    # Symbol
    D.text(v22.x + txtpad, D.y0, "+")

    # Item 3
    v31 = D.vertex([v22.x + 3 * txtpad,  D.y0 - 0.3])
    DW = D.line(v31, v31, **DW_style)

    D.plot()
    plt.show()

**Total running time of the script:** ( 0 minutes  0.049 seconds)



.. only :: html

 .. container:: sphx-glr-footer


  .. container:: sphx-glr-download

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



  .. container:: sphx-glr-download

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


.. only:: html

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

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