How to covert the Phonopy format force constant file FORCE_CONSTANTS to the Alamode format force constant file xxx.xml?

[kingsleylee1203]

Hi Dr. Tadano,
I am using ALAMODE to calculating the lattice thermal conductivity of the 2D materials. It is well known that the ZA branch of 2D materials phonon dispersion should exhibit a quadratic behavior near the center of Brillouin zone in physics. The finate displace approach may not consider the translational and rotational invariance thus may induce a linear-like behavior for ZA branch near the center of Brillouin zone even a U-shaped imaginary frequency for a dynamic stable 2D material.
I have noticed that ALAMODE could not enforce rotational invariance to the force constant, thus I want to use Hiphive package to enforce the translational and rotational invariance. But there is force constant file format convertion problem: Hiphive could not recognize the xxx.xml format of ALAMODE. Thus I used the python scripts you have offered to convert the ALAMODE format force constant file "xxx.xml" to the phonopy format force constant file "FORCE_CONSTANTS" and using phonopy convert the "FORCE_CONSTANTS" to hdf5 format in order to be recognized by Hiphive. Now I have enforced the translational and rotational invariance to the force constants and obatained the corrected "FORCE_CONSTANTS" file.
Next I want to using the corrected force constants for the SCPH calculation, but I could not convert the phonopy format force constant file "FORCE_CONSTANTS" to the ALAMODE format force constant file "xxx.xml" .
Is there any script that could realize the format converting from "FORCE_CONSTANTS" to "xxx.xml" ? If not, could you tell me the specific format of the "xxx.xml" to enable me trying to write a home-made script to realize my demand.
or is there any update realizing enforcing the Born-Huang sum rule for the ALAMODE I have ignored ?

My content is a bit lengthy, and thanks for your patients.
looking for your reply and best wishes!

Kang Li

[ttadano]

Unfortunately, I do not have a script that converts FORCE_CONSTANTS to the Alamode XML file format.

BTW, the ALM code can impose the rotational invariance. To invoke that option, please set the following options:

In &general field,
FCSYM_BASIS=C

In &optmize field,
ICONST=2; ROTAXIS=xyz

[vivekgusain09]

Hi all,
Could you please guide me on how to convert the .xml format second order force constant file to phonopy format as i am facing strange issues when using the converted force constants which i have shared here: #301
i am using the convert_fc2.py script provided in the alamode tools directory but i am not able to identify the reasons causing the failure in correctly converting the second order harmonic force constants. Any kind of help is highly appreciated. Thanks in advanced.