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the band structure of 4H-SiC
Date: 2022/01/05 21:04
Name: Qi Wang

Dear Developers and Users,

I calculated the band structure of 4H-SiC, but the result showed direct band gap , How can I get the indirect band gap?

thank you so much
メンテ
Page: [1]

Re: the bans structure of 4H-SiC ( No.1 )
Date: 2022/01/05 17:55
Name: Naoya Yamaguchi

Hi,

Can you show the input file for reproduction of your issue?

Regards,
Naoya Yamaguchi
メンテ
Re: the band structure of 4H-SiC ( No.2 )
Date: 2022/01/05 21:34
Name: Qi Wang  <466746962@qq.com>

Hi, Mr Naoya Yamaguchi

thank you for your reply.

the main part of the input file is as follows:

Species.Number 2
<Definition.of.Atomic.Species
Si Si7.0-s2p2d1 Si_CA13
C C5.0-s2p2d1 C_CA13
Definition.of.Atomic.Species>

Atoms.Number 16
Atoms.SpeciesAndCoordinates.Unit Ang
<Atoms.SpeciesAndCoordinates
1 C 0.000 0.000 0.000 2.0 2.0
2 Si 0.000 0.000 1.888 2.0 2.0
3 C 0.000 0.000 5.023 2.0 2.0
4 Si 0.000 0.000 6.911 2.0 2.0
5 Si 0.000 1.777 4.400 2.0 2.0
6 C 0.000 1.777 2.511 2.0 2.0
7 Si 1.539 0.889 9.422 2.0 2.0
8 C 1.539 0.889 7.534 2.0 2.0
9 C 3.078 -0.000 0.000 2.0 2.0
10 Si 3.078 -0.000 1.888 2.0 2.0
11 C 3.078 -0.000 5.023 2.0 2.0
12 Si 3.078 -0.000 6.911 2.0 2.0
13 Si 3.078 1.777 4.400 2.0 2.0
14 C 3.078 1.777 2.511 2.0 2.0
15 Si 4.617 0.889 9.422 2.0 2.0
16 C 4.617 0.889 7.534 2.0 2.0
Atoms.SpeciesAndCoordinates>
Atoms.UnitVectors.Unit Ang
<Atoms.UnitVectors
6.156000 0.000000 0.000000
-1.539000 2.665625 0.000000
0.000000 0.000000 10.04500
Atoms.UnitVectors>

scf.XcType GGA-PBE
scf.SpinPolarization off
scf.ElectronicTemperature 0.00
scf.energycutoff 100.0
scf.maxIter 100
scf.EigenvalueSolver band
scf.lapack.dste dstevx
scf.Kgrid 5 5 5
scf.Mixing.Type rmm-diis
scf.Init.Mixing.Weight 0.30
scf.Min.Mixing.Weight 0.001
scf.Max.Mixing.Weight 0.700
scf.Mixing.History 7
scf.Mixing.StartPulay 5
scf.criterion 1.0e-9

Band.dispersion on
<Band.KPath.UnitCell
3.078000 0.000000 0.000000
-1.539000 2.665625 0.000000
0.000000 0.000000 10.04500
Band.KPath.UnitCell>

Band.Nkpath 9
<Band.kpath
25 0.00 0.00 0.00 0.50 0.00 0.00 Γ M
25 0.50 0.00 0.00 0.33 0.33 0.00 M K
25 0.33 0.33 0.00 0.00 0.00 0.00 K Γ
25 0.00 0.00 0.00 0.00 0.00 0.50 Γ A
25 0.00 0.00 0.50 0.50 0.00 0.50 A L
25 0.50 0.00 0.50 0.33 0.33 0.50 L H
25 0.33 0.33 0.50 0.00 0.00 0.50 H A
25 0.50 0.00 0.50 0.50 0.00 0.00 L M
25 0.33 0.33 0.00 0.33 0.33 0.50 K H
Band.kpath>


Regards,
Qi Wang
メンテ
Re: the band structure of 4H-SiC ( No.3 )
Date: 2022/01/06 04:32
Name: Naoya Yamaguchi

Dear Qi Wang,

I guess that you saw the band folding. Therefore, the energy levels at the M-point in the first Brillouin zone for the primitive cell appear at the Γ-point in that for your supercell. The keyword of `Band.KPath.UnitCell` is not used for the band unfolding. Conversely, it might give the undesirable k-paths (See `kpath (converted)` in the standard output).

```
The number of threads in each node for OpenMP parallelization is 1.


*******************************************************
*******************************************************
Welcome to OpenMX Ver. 3.9.2
Copyright (C), 2002-2019, T. Ozaki
OpenMX comes with ABSOLUTELY NO WARRANTY.
This is free software, and you are welcome to
redistribute it under the constitution of the GNU-GPL.
*******************************************************
*******************************************************

3.078000 0.000000 0.000000
-1.539000 2.665625 0.000000
0.000000 0.000000 10.045000

kpath (converted)
(0.000000 0.000000 0.000000) (1.000000 0.000000 0.000000)
(1.000000 0.000000 0.000000) (0.660000 0.330000 0.000000)
(0.660000 0.330000 0.000000) (0.000000 0.000000 0.000000)
(0.000000 0.000000 0.000000) (0.000000 0.000000 0.500000)
(0.000000 0.000000 0.500000) (1.000000 0.000000 0.500000)
(1.000000 0.000000 0.500000) (0.660000 0.330000 0.500000)
(0.660000 0.330000 0.500000) (0.000000 0.000000 0.500000)
(1.000000 0.000000 0.500000) (1.000000 0.000000 0.000000)
(0.660000 0.330000 0.000000) (0.660000 0.330000 0.500000)
```

Regards,
Naoya Yamaguchi
メンテ
Re: the band structure of 4H-SiC ( No.4 )
Date: 2022/01/07 17:37
Name: Qi Wang

Dear Naoya Yamaguchi,

Thank you for your guidance, I calculated the band of primitive cell successfully.

I calculated the band of supercell with Materials Studio software successfully, but I still failed to calculate it with OPENMX.

Now I'm learning the unfolding method for band structures, can this method solve my problem?

thank you for your help.

regards,
Qi Wang

メンテ
Re: the band structure of 4H-SiC ( No.5 )
Date: 2022/01/08 02:12
Name: Naoya Yamaguchi

Dear Qi Wang,

>Now I'm learning the unfolding method for band structures, can this method solve my problem?

If you compare the supercell band structure with the primitive one directly, you can use the unfolding method.

Regards,
Naoya Yamaguchi
メンテ

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