Author Topic: Regarding bandstructure difference between unit cell and repeated cell  (Read 114 times)

0 Members and 1 Guest are viewing this topic.

Offline sonal AGRAWAL

  • Regular ATK user
  • **
  • Posts: 28
  • Country: in
  • Reputation: 0
    • View Profile
Dear sir, I have calculated the bandstructure of unit cell and its repeated cell the bandstructure of both the system are different. I have calculated the bandstructure of unit cell for brillioun zone point X, Z T, Y, G which is in well agreement with reference literature 10.1016/j.physb.2018.02.015. but when I have repeated the cell than the bandstructure is not sane as unit cell. I have tried all possible brillioun zone point. But the bandstructure is not matched. Please help me out
Related Log files and py files are attached
Thanks in advance
Sonal
« Last Edit: September 4, 2020, 07:03 by sonal AGRAWAL »

Offline Jess Wellendorff

  • QuantumWise Staff
  • Supreme ATK Wizard
  • *****
  • Posts: 937
  • Country: dk
  • Reputation: 28
    • View Profile
The brillouin zone points in the repeated cell are not high-symmetry points in the same way as for the minimal cell, so the band paths are different. No surprise there. I suggest you look are the DOS instead; if you normalize properly (e.g. on a per-atom basis), and use well-converged k-point grids for DOS, the DOS should be similar no matter the repetition. 

Offline sonal AGRAWAL

  • Regular ATK user
  • **
  • Posts: 28
  • Country: in
  • Reputation: 0
    • View Profile
Yes sir, Dos is same but the bandstructure is not matching. I have communicated a manuscript with this bandstructure and they are asking about the bandstructure matching. Can you please suggest the high symmetry brilliouin zone point for the bandstructure calculation. How can I defend this problem.
« Last Edit: September 1, 2020, 18:41 by sonal AGRAWAL »

Offline Petr Khomyakov

  • QuantumWise Staff
  • Supreme ATK Wizard
  • *****
  • Posts: 1250
  • Country: dk
  • Reputation: 19
    • View Profile
The band structure should not look the same for a repeated unit cell, since there is band folding for the repeated unit cell, because the Brillouin zone for the repeated unit cell is smaller than that for the original unit cell, meaning that all the bands in the original Brillouin zone has to fold accordingly.  You may take a look at any textbook on Solid State Physics (e.g., by Ashcroft & Mermin) to understand how the Brillouin zone and related band structure folds when going to a repeated unit cell.