mirror of https://github.com/phonopy/phonopy.git
112 lines
3.4 KiB
ReStructuredText
112 lines
3.4 KiB
ReStructuredText
.. _vasp_fd_interface:
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VASP & phonopy calculation
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===========================
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Please follow the page :ref:`tutorial` and :ref:`examples_link`.
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.. _vasp_dfpt_interface:
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VASP-DFPT & phonopy calculation
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===========================================
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How to run
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-----------
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VASP can calculate force constants in real space using DFPT. The
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procedure to calculate phonon properties may be as follows:
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1) Prepare unit cell structure named, e.g., ``POSCAR-unitcell``. The
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following structure is a conventional unit cell of NaCl.
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::
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Na Cl
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1.00000000000000
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5.6903014761756712 0.0000000000000000 0.0000000000000000
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0.0000000000000000 5.6903014761756712 0.0000000000000000
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0.0000000000000000 0.0000000000000000 5.6903014761756712
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4 4
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Direct
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0.0000000000000000 0.0000000000000000 0.0000000000000000
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0.0000000000000000 0.5000000000000000 0.5000000000000000
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0.5000000000000000 0.0000000000000000 0.5000000000000000
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0.5000000000000000 0.5000000000000000 0.0000000000000000
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0.5000000000000000 0.5000000000000000 0.5000000000000000
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0.5000000000000000 0.0000000000000000 0.0000000000000000
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0.0000000000000000 0.5000000000000000 0.0000000000000000
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0.0000000000000000 0.0000000000000000 0.5000000000000000
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2) Prepare a perfect supercell structure from ``POSCAR-unitcell``,
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e.g.,
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::
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% phonopy -d --dim="2 2 2" -c POSCAR-unitcell
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3) Rename ``SPOSCAR`` created in (2) to
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``POSCAR`` (``POSCAR-{number}`` and ``disp.yaml`` files will never be used.)
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::
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% mv SPOSCAR POSCAR
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4) Calculate force constants of the perfect supercell by running VASP
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with ``IBRION = 8`` and ``NSW = 1``. An example of ``INCAR`` for
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insulator may be such like (**just an example!**)::
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PREC = Accurate
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ENCUT = 500
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IBRION = 8
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EDIFF = 1.0e-08
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IALGO = 38
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ISMEAR = 0; SIGMA = 0.1
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LREAL = .FALSE.
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ADDGRID = .TRUE.
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LWAVE = .FALSE.
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LCHARG = .FALSE.
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5) After finishing the VASP calculation, confirm ``vasprun.xml``
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contains ``hessian`` elements, and then create ``FORCE_CONSTANTS``::
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% phonopy --fc vasprun.xml
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6) Run phonopy with the original unit cell ``POSCAR-unitcell`` and
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setting tag ``FORCE_CONSTANTS = READ`` or ``--readfc`` option,
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e.g., as found in ``example/NaCl-VASPdfpt``
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::
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% phonopy --dim="2 2 2" -c POSCAR-unitcell band.conf
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_
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_ __ | |__ ___ _ __ ___ _ __ _ _
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| '_ \| '_ \ / _ \| '_ \ / _ \ | '_ \| | | |
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| |_) | | | | (_) | | | | (_) || |_) | |_| |
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| .__/|_| |_|\___/|_| |_|\___(_) .__/ \__, |
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|_| |_| |___/
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1.1
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Band structure mode
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Settings:
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Force constants: read
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Supercell: [2 2 2]
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Primitive axis:
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[ 0. 0.5 0.5]
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[ 0.5 0. 0.5]
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[ 0.5 0.5 0. ]
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Spacegroup: Fm-3m (225)
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Paths in reciprocal reduced coordinates:
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[ 0.00 0.00 0.00] --> [ 0.50 0.00 0.00]
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[ 0.50 0.00 0.00] --> [ 0.50 0.50 0.00]
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[ 0.50 0.50 0.00] --> [-0.00 -0.00 0.00]
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[ 0.00 0.00 0.00] --> [ 0.50 0.50 0.50]
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.. |NaCl-VASPdfpt| image:: NaCl-VASPdfpt.png
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:scale: 50
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|NaCl-VASPdfpt|
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