def symmetrize_force_constants(force_constants, level=1):
"""Symmetry force constants by translational and permutation symmetries.
Note
----
Schemes of symmetrization are slightly different between C and
python implementations. If these give very different results, the
original force constants are not reliable anyway.
Parameters
----------
force_constants: ndarray
Force constants. Symmetrized force constants are overwritten.
dtype=double
shape=(n_satom,n_satom,3,3)
primitive: Primitive
Primitive cell
level: int
Controls the number of times the following steps repeated:
1) Subtract drift force constants along row and column
2) Average fc and fc.T
"""
try:
import phonopy._phonopy as phonoc
phonoc.perm_trans_symmetrize_fc(force_constants, level)
except ImportError:
for i in range(level):
set_translational_invariance(force_constants)
set_permutation_symmetry(force_constants)
set_translational_invariance(force_constants)
def symmetrize_force_constants(force_constants, iteration=1):
"""Symmetry force constants by translational and permutation symmetries.
The way of doing is currently different between C and python
implementations. If these give very different results, the
original force constants are not reliable anyway. The one
implemented in C is simpler and so considered better.
"""
try:
import phonopy._phonopy as phonoc
phonoc.perm_trans_symmetrize_fc(force_constants)
except ImportError:
for i in range(iteration):
set_permutation_symmetry(force_constants)
set_translational_invariance(force_constants)