error while interpolation of 2x2x2 SSCHA dyn_mat using a 4x4x4 harmonic dyn_mat #79
Description
Discussed in #74
Originally posted by matukumilli March 29, 2022
Hi,
The workaround suggested by Dr. Lorenzo in an earlier thread worked well. In order to avoid SSCHA -ve frequencies at finite q points one has to interpolate SSCHA dyn_mat using a harmonic dyn_mat calculated on a finer q-mesh than SSCHA q-mesh.
However, when I try this interpolation way to avoid -ve freq error, for tetragonal SrTiO3, I getting this below error:
....
...
Iter # 128 ====
Sum on 3rd= 0.844989E-12 Imp. ASR on 3rd: => delta FC= 0.844988E-12
Imp. permut sym: => delta FC= 0.800810E-12
Convergence reached within threshold: 0.100000E-11
Total FC relative variation: 0.128277E+00
Time elapsed for imposing ASR: 186.2998547554016 s
============================================================
WORKING ON: [0. 0. 0.]
SUPERCELL SIZE: 2 2 2
NAT: 10
The unit cell:
5.5080868904697313 7.3440103850181005E-003 0.0000000000000000
3.0484109872987837E-002 5.5080073591324155 0.0000000000000000
-2.7692854120418908 -2.7576755993832940 3.8814121235103820
Total weight: 7.6666666666666670
NR1,2,3 = 2 2 2
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
Error in routine frc_blk (1):
wrong total_weight
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
stopping ...
STOP 1
I couldn't able to figure out the reason for this. Need your help.
Original harmonic dyn_mat calculated on 2x2x2 q-mesh; to avoid the -ve freq in SSCHA dyn_mat, I tried to interpolate the difference between SSCHA and harmonic dyn_mat using harmonic dyn_mat on 4x4x4 q-mesh.
Input script:
from future import print_function
from future import division
import cellconstructor as CC
import cellconstructor.Phonons
import sscha, sscha.Ensemble
import cellconstructor as CC
import cellconstructor.ForceTensor
import cellconstructor.Structure
import cellconstructor.Spectral
import numpy as np
import ase
from ase.calculators.espresso import Espresso
from ase.visualize import view
dyn = CC.Phonons.Phonons("../dyn_pop3_",6)
supercell = dyn.GetSupercell()
tensor3 = CC.ForceTensor.Tensor3(dyn.structure,
dyn.structure.generate_supercell(supercell),
supercell)
d3 = np.load("d3_realspace_sym.npy")*2.0
tensor3.SetupFromTensor(d3)
tensor3.Center(Far=2)
tensor3.Apply_ASR()
k_grid=[10, 10, 10]
path = ase.dft.kpoints.bandpath("GXPNGZS1", dyn.structure.unit_cell, npoints = 150)
qpath = path.cartesian_kpts()
harm_dyn = CC.Phonons.Phonons("../../../matdyn", 6)
harm_dyn_fine_grid = CC.Phonons.Phonons("matdyn_4x/matdyn", 24)
new_cell = harm_dyn_fine_grid.GetSupercell()
big_dyn = dyn.Interpolate( dyn.GetSupercell(), new_cell, support_dyn_coarse = harm_dyn, support_dyn_fine = harm_dyn_fine_grid)
big_dyn.ForcePositiveDefinite()
CC.Spectral.get_static_correction_along_path(dyn=big_dyn,
tensor3=tensor3,
k_grid=k_grid,
q_path = qpath,
filename_st="v2_v2+d3static_freq-GXPNGZS1.dat",
T =50.0,
print_dyn = False)
Regards,
Prasad