Unable to read force_constant

hiPhive
1

Dear hiPhive developer,

I am a new user of hiPhive and would like to apply the rotational sum rule on the 2nd order force constant of two-dimensional material. After getting the force_constants.hdf5 file by phonopy I used the following script to generate a further corrected force file.

from ase.io import read
from hiphive import ClusterSpace, ForceConstantPotential, enforce_rotational_sum_rules
from hiphive.cutoffs import estimate_maximum_cutoff
from hiphive.utilities import extract_parameters
from hiphive import ForceConstants, ClusterSpace, ForceConstantPotential
from hiphive import enforce_rotational_sum_rules
from hiphive.utilities import extract_parameters

prim = read(‘POSCAR’)
supercell = read(‘SPOSCAR’)
max_cutoff = estimate_maximum_cutoff(supercell) - 0.01
cutoffs = [max_cutoff] # only second order needed
cs = ClusterSpace(prim, cutoffs)
phonopy
fcs = ForceConstants.read_phonopy(supercell,‘force_constants.hdf5’)
parameters = extract_parameters(fcs, cs)
parameters_rot = enforce_rotational_sum_rules(cs, parameters, [‘Huang’, ‘Born-Huang’])
fcp = ForceConstantPotential(cs, parameters_rot)
fcs = fcp.get_force_constants(supercell)
fcs.write_to_phonopy(‘fc2_rotinv.hdf5’, format=‘hdf5’)

But error occurred
Traceback (most recent call last):
** File “Fconversion”, line 18, in **
** fcs = ForceConstants.read_phonopy(supercell,‘force_constants.hdf5’)**
** File “/iitjhome/kukreti1/.local/lib/python3.8/site-packages/hiphive-1.1-py3.8.egg/hiphive/force_constants.py”, line 348, in read_phonopy**
** File “/iitjhome/kukreti1/.local/lib/python3.8/site-packages/hiphive-1.1-py3.8.egg/hiphive/force_constants.py”, line 288, in from_arrays**
ValueError: fc2 array has wrong shape

I am unable to solve this issue. Kindly tell me the way so that I can get corrected force constants.

Thank You

Regards
Sumit Kukreti
Ph.D. Scholar
IIT Jodhpur INDIA

2

The ValueError comes from the fc2_array.shape != (n_atoms, n_atoms, 3, 3).
So I think its likely that your force_constants.hdf5 is written in a compact format and can be fixed in phonopy by adding a flag, see the phonopy doc.

If this is not the problem then it could be due to providing the wrong (too large or small) supercell which could cause this error.

3

Thank you, sir,
Now it worked after considering full force constants.
Yes, I took compact format which is a default that is why the error occurred.

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