[Pw_forum] There are lines where there shouldn't be in bandstructure diagrams

[Dae Kwang Jun]

Dear all,

I need your help. I am able to calculate the band structure of a bulk
material. However, I keep getting lines between bands. The problem is worse
if I use K_POINTS {automatic} in the scf calculation. The lines still
appear even after setting a k point path on K_POINTS. Here is the input
file for scf calculation using a k point path for bulk wurtzite ZnO. The
functional used is Perdew Wang LDA.

&CONTROL
calculation = 'scf'
verbosity = 'high'
restart_mode = 'from_scratch'
wf_collect = .TRUE.
tstress = .TRUE.
tprnfor = .TRUE.
outdir = '/home/jud11/post_proc/files'
pseudo_dir = '/home/jud11/post_proc/espresso-5.4.0/pseudo'
prefix = 'ZnO'
/
&SYSTEM
ibrav = 4
a = 3.24
c = 5.2
nat = 4
ntyp = 2
nbnd = 60
ecutwfc = 70
occupations = 'fixed'
/
&ELECTRONS
diagonalization = 'david'
mixing_beta = 0.8
/
ATOMIC_SPECIES
Zn    65.38    Zn.pw-mt_fhi.UPF
O     15.99    O.pw-mt_fhi.UPF
ATOMIC_POSITIONS {angstrom}
Zn    0.000000    1.870615    0.000000
Zn    1.620000    0.935307    2.600000
O    0.000000    1.870615    1.989000
O    1.620000    0.935307    4.589000
K_POINTS {crystal_b}
8
0.0000    0.0000    0.5000    1000
0.5000    0.0000    0.5000    1000
0.5000    0.0000    0.0000    1000
0.0000    0.0000    0.0000    1000
0.0000    0.0000    0.5000    1000
0.6666    0.3333    0.5000    1000
0.6666    0.3333    0.0000    1000
0.0000    0.0000    0.0000    1000

I also have attached two pictures of the band structure. One is zoomed in
make the lines more visible. I have used the same path that is used in this
website:
https://www.tcd.ie/Physics/people/Charles.Patterson/research_projects/zinc_cobolt_oxide.php
What am I doing wrong?

Sincerely,

Dae Kwang Jun
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