mirror of https://github.com/phonopy/phonopy.git
91 lines
2.8 KiB
ReStructuredText
91 lines
2.8 KiB
ReStructuredText
.. _castep_interface:
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CASTEP & phonopy calculation
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============================
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Examples to use phonopy with CASTEP as the force calculator are found
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at ``example/NaCl-castep`` and ``example/Cr-castep``.
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The followings are the copies of ``README`` contents in these example
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directories.
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These are contriubted by `@ladyteam <https://github.com/ladyteam>`_.
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NaCl-castep
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-----------
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This is step-by-step example how to calculate phonon dispertion with
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CASTEP.
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1. Generate supercell based on structrural parameters given in
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``unitcell.cell`` file by running::
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% phonopy -d --dim="2 2 2" --castep -c unitcell.cell
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In this example file ``unitcell.cell`` contains initial spin values in
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``positions_frac`` BLOCK. As well as the value of the U parameter in
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LDA+U approximation.
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2. Use ``make_displ_dirs.sh`` bash script to make directories with input
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files needed to calculate FORCES for supercells.
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::
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% make_displ_dirs.sh supercell.param tail.cell
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Please note file supercell.param is the standart CASTEP file with
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paremeters (convergence criteria, Ecut, functional name etc.). The
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file with name ``tail.cell`` contains k-mesh description, U parameter
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value, symmetry operation E, and name of pseudopotential.
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3. Run CASTEP calculation in ``displ-001`` directory
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4. Generate ``FORCE_SETS`` file by running::
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% phonopy --castep -f displ-001/supercell.castep displ-002/supercell.castep
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5. Finally plot phonon bandstructure by running the following command::
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% phonopy --castep -c unitcell.cell -p band.conf
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Cr-castep
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---------
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This is step-by-step example how to calculate phonon dispertion with CASTEP.
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Spin-polarization example.
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1. Generate supercell based on structrural parameters given in
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``unitcell.cell`` file by running::
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% phonopy -d --dim="2 2 2" --castep -c unitcell.cell
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In this example file ``unitcell.cell`` contains initial spin values in
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``positions_frac`` BLOCK. As well as the value of the U parameter in
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LDA+U approximation.
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2. Use ``make_displ_dirs.sh`` bash script to make directories with input
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files needed to calculate FORCES for supercells.
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::
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% make_displ_dirs.sh supercell.param tail.cell
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Please note file ``supercell.param`` is the standart CASTEP file with
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paremeters (convergence criteria, Ecut, functional name etc.). The
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file with name ``tail.cell`` contains k-mesh description, U parameter
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value, symmetry operation E, and name of pseudopotential.
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3. Run CASTEP calculation in ``displ-001`` directory
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4. Generate ``FORCE_SETS`` file by running::
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% phonopy --castep -f displ-001/supercell.castep
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5. Finally plot phonon bandstructure by running the following command:
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::
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% phonopy --dim="2 2 2" --pa="-1/2 1/2 1/2 1/2 -1/2 1/2 1/2 1/2 -1/2" --castep -c unitcell.cell --band="1/2 -1/2 1/2 0 0 0 1/4 1/4 1/4" -p
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