[QE-users] Puzzle in calculate bandstructure

[Vahid Askarpour]

I had this problem before and the solution was to choose the number of divisions between high-symmetry points proportional to their lengths. So if G-X is the longest in BZ, the number of divisions for G-X would be the largest. QE gurus may know why this happens but I don’t.

Cheers,
Vahid

Vahid Askarpour
Department of physics and atmospheric science
Dalhousie University
Halifax, NS
CANADA

On Aug 11, 2024, at 11:00 AM, wangzongyi via users <users at lists.quantum-espresso.org> wrote:

CAUTION: The Sender of this email is not from within Dalhousie.
Dear all
  I am trying to calculate the band structure of Bi2Se3 in the procession below:
1.mpirun -np $SLURM_NTASKS pw.x < scf.in > scf.out
2.mpirun -np $SLURM_NTASKS pw.x < bands.in > bands.out
3.mpirun -np $SLURM_NTASKS bands.x < pp.bands.in > pp.bands.out

However, after I finished this procession, the pp.bands.out file showed me the following information:


     high-symmetry point:  0.0000 0.0000 0.0000   x coordinate   0.0000
     high-symmetry point:  0.0000 0.0000 0.2167   x coordinate   0.2167
     high-symmetry point:  0.0000-0.5774 0.1445   x coordinate   0.2167
     high-symmetry point:  0.0000 0.0000 0.0000   x coordinate   0.8119
     high-symmetry point: -0.5000-0.2887 0.0722   x coordinate   1.3937

It is difficult for me to understand why the x coordinate of the second point and the third point turned out to be same. I am wondering whether I have made any error in my bands.in file . The bands.in file is shown in the following lines. It is worth to mention that even if I change the number before !L from 20 to 1, the second and the third coordinate are still the same.


&CONTROL
  calculation = 'bands'
  etot_conv_thr =   5.0000000000d-05
  forc_conv_thr =   1.0000000000d-04
  outdir = './out/'
  prefix = 'Bi2Se3'
  pseudo_dir = '../pseudo/'
  tprnfor = .true.
  tstress = .true.
  verbosity = 'high'
/
&SYSTEM
  degauss =   1.4699723600d-02
  ecutrho =   3.6000000000d+02
  ecutwfc =   4.5000000000d+01
  ibrav = 0
  nat = 5
  nosym = .true.
  ntyp = 2
  nbnd = 120
  occupations = 'smearing'
  smearing = 'cold'
  noncolin = .true.
  lspinorb = .true.
  starting_magnetization(1) =   0.0d0
  starting_magnetization(2) =   0.0d0
/
&ELECTRONS
  conv_thr =   1.0000000000d-09
  electron_maxstep = 80
  mixing_beta =   4.0000000000d-01
/
ATOMIC_SPECIES
Bi     208.9804 Bi.NC.FR.PBEsol.stringent.UPF
Se     78.96 Se.NC.FR.PBEsol.stringent.UPF
ATOMIC_POSITIONS crystal
Bi           0.3990000000       0.3990000000       0.6970000000
Bi           0.6010000000       0.6010000000       0.3030000000
Se          -0.0000000000      -0.0000000000       0.5000000000
Se           0.2060000000       0.2060000000       0.1180000000
Se           0.7940000000       0.7940000000       0.8820000000
K_POINTS crystal_b
5
0.00000 0.00000 0.0000 50 !G
0.00000 0.00000 0.5000 20 !Z
0.50000 0.50000 0.0000 50 !F
0.00000 0.00000 0.0000 50 !G
0.50000 0.00000 0.0000 20 !L
CELL_PARAMETERS angstrom
     -2.0690000000      -3.5836140000       0.0000000000
      2.0690000000      -3.5836140000       0.0000000000
      0.0000000000       2.3890750000       9.5466670000

And my pp.bands.in file is in the following lines, I wish you could look through it, too.

&BANDS
  outdir = './out'
  prefix = 'Bi2Se3'
  filband = 'Bi2Se3_prim.dat'
/

I don't know what problem lead to this error coordinate. Could you please help me?

Thank you very much!

Zongyi Wang
_______________________________________________
The Quantum ESPRESSO community stands by the Ukrainian
people and expresses its concerns about the devastating
effects that the Russian military offensive has on their
country and on the free and peaceful scientific, cultural,
and economic cooperation amongst peoples
_______________________________________________
Quantum ESPRESSO is supported by MaX (www.max-centre.eu<http://www.max-centre.eu/>)
users mailing list users at lists.quantum-espresso.org<mailto:users at lists.quantum-espresso.org>
https://lists.quantum-espresso.org/mailman/listinfo/users

-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.quantum-espresso.org/pipermail/users/attachments/20240811/0366e27e/attachment.html>