.. DO NOT EDIT.
.. THIS FILE WAS AUTOMATICALLY GENERATED BY SPHINX-GALLERY.
.. TO MAKE CHANGES, EDIT THE SOURCE PYTHON FILE:
.. "gallery/plot_qha.py"
.. LINE NUMBERS ARE GIVEN BELOW.

.. only:: html

    .. note::
        :class: sphx-glr-download-link-note

        :ref:`Go to the end <sphx_glr_download_gallery_plot_qha.py>`
        to download the full example code.

.. rst-class:: sphx-glr-example-title

.. _sphx_glr_gallery_plot_qha.py:


Quasi-harmonic approximation
============================

This example shows how to use the GSR.nc and PHDOS.nc files computed with different volumes
to compute thermodynamic properties within the quasi-harmonic approximation.

.. GENERATED FROM PYTHON SOURCE LINES 9-48



.. rst-class:: sphx-glr-horizontal


    *

      .. image-sg:: /gallery/images/sphx_glr_plot_qha_001.png
         :alt: Energies as a function of volume for different T
         :srcset: /gallery/images/sphx_glr_plot_qha_001.png
         :class: sphx-glr-multi-img

    *

      .. image-sg:: /gallery/images/sphx_glr_plot_qha_002.png
         :alt: Thermal expansion coefficient as a function of T
         :srcset: /gallery/images/sphx_glr_plot_qha_002.png
         :class: sphx-glr-multi-img

    *

      .. image-sg:: /gallery/images/sphx_glr_plot_qha_003.png
         :alt: Volume as a function of T
         :srcset: /gallery/images/sphx_glr_plot_qha_003.png
         :class: sphx-glr-multi-img

    *

      .. image-sg:: /gallery/images/sphx_glr_plot_qha_004.png
         :alt: Phonon band structures with color depending on T
         :srcset: /gallery/images/sphx_glr_plot_qha_004.png
         :class: sphx-glr-multi-img


.. rst-class:: sphx-glr-script-out

 .. code-block:: none

    WARNING combiplot: Bands have different number of k-points:
    [83, 81]






|

.. code-block:: Python

    import os
    import abipy.data as abidata

    from abipy.dfpt.phonons import PhononBands
    from abipy.dfpt.qha import QHA

    # We use a list of GSR.nc and PHDOS.nc files corresponding to different isotropic strains.
    # These files are shipped with AbiPy so that we don't need to run calculations from scratch.
    strains = [-4, -2, 0, 2, 4, 6]
    dirpath = os.path.join(abidata.dirpath, "refs", "si_qha")

    gsr_paths = [os.path.join(dirpath, "mp-149_{:+d}_GSR.nc".format(s)) for s in strains]
    dos_paths = [os.path.join(dirpath, "mp-149_{:+d}_PHDOS.nc".format(s)) for s in strains]

    # Initialize QHA object from files.
    # The PHDOS.nc files can be obtained from the DDB used ddb.anaget_phbst_and_phdos_files(...)
    qha = QHA.from_files(gsr_paths, dos_paths)

    # To change the default EOS (vinet), use
    #qha.set_eos("murnaghan")

    qha.plot_energies(title="Energies as a function of volume for different T")

    qha.plot_thermal_expansion_coeff(title="Thermal expansion coefficient as a function of T")

    qha.plot_vol_vs_t(title="Volume as a function of T")

    # Fake temperatures to test the plotting function.
    phbs_list = [PhononBands.from_file(os.path.join(dirpath, "mp-149_{:+d}_PHBST.nc".format(s))) for s in
                 strains[2:4]]

    qha.plot_phbs(phbs_list, temperatures=[10, 20], title="Phonon band structures with color depending on T")

    # Here we build a Phonopy QHA object.
    # Cannot run this code because it breaks sphinx-gallery

    #qha_phonopy = qha.get_phonopy_qha(tstop=500, num=11)
    #qha_phonopy.run()
    #qha_phonopy.plot_bulk_modulus_temperature().show()


.. rst-class:: sphx-glr-timing

   **Total running time of the script:** (0 minutes 1.328 seconds)


.. _sphx_glr_download_gallery_plot_qha.py:

.. only:: html

  .. container:: sphx-glr-footer sphx-glr-footer-example

    .. container:: sphx-glr-download sphx-glr-download-jupyter

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

    .. container:: sphx-glr-download sphx-glr-download-python

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

    .. container:: sphx-glr-download sphx-glr-download-zip

      :download:`Download zipped: plot_qha.zip <plot_qha.zip>`


.. only:: html

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

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