[Questions for Z2pack] Dear developers,

[이지우]

Dear developers,

Hello.

I am now trying to get a z2-invariant using VASP code but
I've got some problems in plotting the WCC using the Z2pack.

Firstly, I prepared the converged CHGCAR in advance and
got WCC using the z2-implemented VASP code.

The material is Bi bulk structure.
And this is what I got.

[image: image.png]


And this is the result provided in z2pack GitHub.

[image: image.png]

The main problem is where i made highlight with red circles.
There are some condensed horizontal points that also middle point of
largest gap (blue diamonds) are changed.
In addition, the points near the two extreme x-axis ends are increased.
Except for those, other points look very similar with z2pack provided
result.

I've tested few options,

   - pos_tol
   - move_tol
   - gap_tol
   - num_lines
   - min_neighbour_dist

however, they doesn't remove the condensed horizontal points.

Are there any ways/solutions that I can make a try?

------------------------------------------------------------------------------------
This the "run.py" I have used.

#!/home/woosun/Programs/Python3/bin/python3
import os
import matplotlib
matplotlib.use('Agg')
import matplotlib.pyplot as plt
import z2pack

# Creating the System. Note that the SCF charge file does not need to be
# copied, but instead can be referenced in the .files file.
# The k-points input is appended to the .in file
# The command (mpirun ...) will have to be replaced to match your system.
system = z2pack.fp.System(
    input_files=["input/CHGCAR", "input/INCAR", "input/POSCAR",
"input/POTCAR", "input/wannier90.win" ],
    kpt_fct=z2pack.fp.kpoint.vasp,
    kpt_path="KPOINTS",
    command="mpirun
 /home/woosun/Source_codes/vasp544/vasp.5.4.4_for_z2/bin/vasp_ncl > stdout"
)

if not os.path.exists('./results'):
    os.mkdir('./results')
if not os.path.exists('./plots'):
    os.mkdir('./plots')

# Running the WCC calculation - standard settings
result_0 = z2pack.surface.run(
    system=system,
    surface=lambda s, t: [0, s / 2, t],
    save_file = './results/res_0.p',
    load=True
)
result_1 = z2pack.surface.run(
    system=system,
    surface=lambda s, t: [0.5, s / 2, t],
    save_file = './results/res_1.p',
    load=True
)

# Plotting WCC evolution
fig, ax = plt.subplots(1, 2, sharey=True, figsize = (9,5))

z2pack.plot.wcc(result_0, axis=ax[0])
z2pack.plot.wcc(result_1, axis=ax[1])
plt.savefig('plots/plot.pdf', bbox_inches = 'tight')

print('Z2 topological invariant at kx = 0:
{0}'.format(z2pack.invariant.z2(result_0)))
print('Z2 topological invariant at kx = 0.5:
{0}'.format(z2pack.invariant.z2(result_1)))

------------------------------------------------------------------------------------

Thank you so much for reading the long email.

I will look forward to having your reply. :)

Sincerely,
Jiwoo Lee.

-- 
*JIWOO LEE* | Research Associate
Materials Theory Group | Department of Materials Science & Engineering
연세대학교 신소재공학과 재료 이론 연구실
통합과정 이지우

*YONSEI UNIVERSITY*
50 Yonsei-Ro | Seodaemun-Gu | 120-749 | Seoul | KOREA
*M* +82-10-7282-5106 | *E* jiwoo2231 at yonsei.ac.kr | *W*
http://www.materials-theory.org/
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