Dear Eyvaz Isaaev
?
??? I want to calculate electronic band structure of w-ZnO (1x1x2 super cell).
But output band strcuture is overlaped. Whereas the band structure of w-ZnO
unit cell is same as theoretical and experimental. I make this supercell using
PHON code. Due to increase in cell along z-axis? I increase its lattice
parameter c 2 times in inputs (celldm=2*c/a). The inputs are attcahed below.
&control
Title = 'ZnO , hcp,a=3.2500,c=5.206
,c/a=1.6103125',
calculation ='scf'
restart_mode='from_scratch',
pseudo_dir =
'/root/Pwscf/pseudo/',
outdir
='/root/Pwscf/scratch/'
prefix ='ZnO'
tstress = .false.
tprnfor = .false.
/
&system
ibrav= 4,
celldm(1) = 6.132075472,
celldm(3) = 1.601846154,
nat =4,
ntyp =2,
ecutwfc =25.0,
ecutrho =300.0
occupations ='smearing',
smearing='methefessel_paxton',
degauss = 0.02,
/
&electrons
diagonalization='cg' ,
conv_thr = 1.0e-8
mixing_beta = 0.7
/
ATOMIC_SPECIES
Zn 65.409 Zn.pz-van_ak.UPF
O 15.9994 O.pz-van_ak.UPF
ATOMIC_POSITIONS (crystal)
Zn 0.333333333 0.666666667
0.0000000
O 0.333333333 0.666666667
0.3817000
Zn 0.666666667 0.333333333
0.5000000
O 0.666666667 0.333333333
0.8817000
K_POINTS (automatic)
7 7 7? 0 0 0
This plot (after changing scf to nscf)
is same as experimental and theoretical
BUT
when I make a cell of 8 atoms (1x1x2
supercell)
input is as below
&control
calculation ='nscf' <= or bands
restart_mode='from_scratch',
pseudo_dir =
'/root/Pwscf/pseudo/',
outdir
='/root/Pwscf/scratch/'
prefix ='ZnO'
tstress = .false.
tprnfor = .true.
/
&system
ibrav = 4,
celldm(1) = 6.132075472,
celldm(3) = 3.203692308,
(due to increase in size along Z-direction C= 2*c )
nat = 8,
ntyp = 2,
ecutwfc = 25.0,
ecutrho = 300.0
occupations ='smearing',
smearing ='methefessel_paxton',
degauss =0.02?nbnd=20?nosym=.true.
/
&electrons
diagonalization='cg'
,mixing_mode='plain',
conv_thr = 1.0e-8
mixing_beta = 0.7
/
ATOMIC_SPECIES
Zn 65.38 Zn.pz-van_ak.UPF
O 16.00 O.pz-van_ak.UPF
ATOMIC_POSITIONS (crystal)
Zn 0.333333333 0.666666667
0.000000000
Zn 0.333333333 0.666666667
0.500000000
Zn 0.666666667 0.333333333
0.250000000
Zn 0.666666667 0.333333333
0.750000000
O 0.333333333 0.666666667
0.190850000
O 0.333333333 0.666666667
0.690850000
O 0.666666667 0.333333333
0.440850000
O 0.666666667 0.333333333
0.940850000
K_POINTS
32
?? 0.0?? 0.0? 0.5? 1
?? 0.1? -0.1? 0.1? 2
?? 0.2? -0.2? 0.2? 3
?? 0.3? -0.3? 0.3? 4
?? 0.4? -0.4? 0.4? 5
?? 0.5? -0.5? 0.5? 6
?? 0.5? -0.5? 0.4? 7
?? 0.5? -0.5? 0.3? 8
?? 0.5? -0.5? 0.2? 9
?? 0.5? -0.5? 0.1? 10
?? 0.5? -0.5? 0.0? 11
?? 0.4? -0.4? 0.0? 12
?? 0.3? -0.3? 0.0? 13
?? 0.2? -0.2? 0.0? 14
?? 0.1? -0.1? 0.0? 15
?? 0.0?? 0.0? 0.0? 16
?? 0.0?? 0.0? 0.1? 17
?? 0.0?? 0.0? 0.2? 18
?? 0.0?? 0.0? 0.3? 19
?? 0.0?? 0.0? 0.4? 20
?? 0.0?? 0.0? 0.5? 21
?? 0.11? 0.11? 0.5 22
?? 0.22? 0.22? 0.5 23
?? 0.33? 0.33? 0.5 24
?? 0.33? 0.33? 0.4 25
?? 0.33? 0.33? 0.3 26
?? 0.33? 0.33? 0.2 27
?? 0.33? 0.33? 0.1 28
?? 0.33? 0.33? 0.0 29
?? 0.22? 0.22? 0.0 30
?? 0.11? 0.11? 0.0 31
?? 0.00? 0.00? 0.0 32
After changing scf to bands the
electronic structure is metallic (no band gap) and a I get different
electronic structure . Now please guide me how I can get true
electronic structure.
Thanking in Advance
Muhammad Zafar
PhD Scholar
Department of Physics
The Islamia University of Bahawalpur,Pakistan
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