This code is designed to allow modelling codes that can perform phonon calculations to be interfaced to the Phonopy code[1] for post processing.
In a finite-displacement phonon calculation, a set of force-constant matrices Φαβ(jl,j'l') are computed in real space and used to construct dynamical matrices Dαβ(jj',q), which when diagonalised give the vibrational frequencies ω(q,v) and eigenvectors W(q,v).
PhonopyImporter uses the DynmatToForceConstants API from Phonopy to reverse this workflow: the frequencies and eigenvectors from a completed phonon calculation are used to reconstruct the dynamical matrices, which are then reverse-transformed to a set of force constant matrices that can be used for further post-processing in Phonopy.
Phonopy-Importer is supplied as a Python module, PhonopyImporter, and a set of command-line scripts.
For infrequent use, it is probably most straightforward to clone the repository, copy the PhonopyImporter folder and the command-line script(s) you need to your working directory, and call them there.
Alternatively, code can be installed by adding the root folder of the repository to the PATH and PYTHONPATH variables, e.g.:
> export PATH=${PATH}:/mnt/d/Repositories/Phono3py-Power-Tools/PhonopyImporter
> export PYTHONPATH=${PYTHONPATH}:/mnt/d/Repositories/Phono3py-Power-Tools/PhonopyImporterPhonopyImporter uses the Phonopy Python API, so Phonopy must be installed to use it, and also requires NumPy.
The castep2phonopy script reads a CASTEP .phonon file and extracts a structure (POSCAR.vasp) and set of force constants (FORCE_CONSTANTS) that can be used with Phonopy.
> castep2phonopy -h
usage: castep2phonopy [-h] -s <seedname> -d <dim_1 dim_2 dim_3>
Convert a CASTEP .phonon file to a POSCAR and FORCE_CONSTANTS file for post-
processing in Phonopy
optional arguments:
-h, --help show this help message and exit
-s <seedname>, --seedname <seedname>
CASTEP .phonon file <seedname>.phonon (e.g.
--seedname="castep")
-d <dim_1 dim_2 dim_3>, --dim <dim_1 dim_2 dim_3>
Equivalent supercell expansion [dim_1, dim_2, dim_3]
for building force constants (e.g. --dim="1 1 1")
For example, to convert a Γ-point CASTEP calculation output into "castep.phonon":
> castep2phonopy -s castep --dim="1 1 1"
At the time of writing, this code has only been tested for Γ-point calculations in CASTEP. If you encounter bugs while using this code, please let us know - it will speed up the process a lot if you can provide a detailed description of the problem and input file(s) that reproduce the error.
We are also happy to take requests to support other codes that do not have a Phonopy interface. If you would like us to add support for another code, please let us know - again, a detailed description of the output format will be helpful.