[Pw_forum] Problem with the Band Structure Calculation

[Gabriele Sclauzero]

Are you absolutely sure that the atomic configuration and k-point path are the same as 
those in the paper?

Maybe K_POINTS in the bands calculation needs the 'CRYSTAL' option?

GS

潘登 wrote:
> Dear All,
> 
>    I was trying to calculate the band structure of the BaNi2As2 which
> had been calculated in the paper 0809.0499v2 on the arxiv.I could not
> repeat the same struture.The  BaNi2As2 occurs in a body centered
> tetragonal structure (I4/mmm) with Ba,Ni and As at the positions
> 2a(0,0,0),4d (0.5,0,0.25)and 4e(0,0,z).Here z equels 0.3476 by the
> experimental result.The lattice parameters are a=4.112 A and c=11.54
> A.
> Any comment about my input of this system?
> my input of scf run:
> 
>  &control
>      calculation = 'scf'
>      restart_mode='from_scratch'
>      prefix='BaNiAs',
>      pseudo_dir = '/disk2/xgwan/Quantum-Espresso/espresso-4.0.3/pseudo/',
>      outdir='/disk2/xgwan/tmp/'
>  /
>  &system
>      ibrav=6,
>      celldm(1)=7.7702,
>      celldm(3)=2.806,
>      nat=10,
>      ntyp=3,
>      ecutwfc = 40.0,
>      ecutrho = 400.0,
>      occupations= 'tetrahedra'
>  /
>  &electrons
>      diagonalization = 'cg'
>      mixing_beta = 0.7
>      conv_thr =  1.0d-6
>  /
> ATOMIC_SPECIES
>  Ba 137.327 Ba.pbe-nsp-van.UPF
>  Ni 58.6934 Ni.pbe-nd-rrkjus.UPF
>  As 74.9216 As.pbe-n-van.UPF
> ATOMIC_POSITIONS crystal
>  Ba 0.0000 0.0000  0.0000
>  Ba 0.5000 0.5000  0.5000
>  Ni 0.0       0.5        0.25
>  Ni 0.5       0.0        0.75
>  Ni 0.5       0.0        0.25
>  Ni 0.0       0.5        0.75
>  As 0.0000 0.0000  0.3476
>  As 0.0000 0.0000  0.6524
>  As 0.5000 0.5000  0.8476
>  As 0.5000 0.5000  0.1524
> K_POINTS {automatic}
>   8 8 8 0 0 0
> 
> And my input of band calculation ,bands.x,plotband.x if helps:
> input of band calculation
>  &control
>      calculation = 'bands'
>      prefix='BaNiAs',
>      pseudo_dir = '/disk2/xgwan/Quantum-Espresso/espresso-4.0.3/pseudo/',
>      outdir='/disk2/xgwan/tmp/'
>      wf_collect=.true.
>  /
>  &system
>      ibrav=6,
>      celldm(1)=7.7702,
>      celldm(3)=2.806,
>      nat=10,
>      ntyp=3,
>      ecutwfc = 40.0,
>      ecutrho = 400.0,
>      occupations= 'tetrahedra'
>  /
>  &electrons
>      diagonalization = 'cg'
>      mixing_beta = 0.7
>      conv_thr =  1.0d-6
>  /
> ATOMIC_SPECIES
>  Ba 137.327 Ba.pbe-nsp-van.UPF
>  Ni 58.6934 Ni.pbe-nd-rrkjus.UPF
>  As 74.9216 As.pbe-n-van.UPF
> ATOMIC_POSITIONS crystal
> Ba 0.5000 0.5000 0.5000
> Ni 0.5000 0.0000 0.2500
> Ni 0.0000 0.5000 0.2500
> Ni 0.0000 0.5000 0.7500
> Ni 0.5000 0.0000 0.7500
> As 0.0000 0.0000 0.3476
> As 0.0000 0.0000 0.6524
> As 0.5000 0.5000 0.8476
> As 0.5000 0.5000 0.1524
> K_POINTS
> 31
> -0.50  0.50  0.50  1
> -0.45  0.45  0.45  2
> -0.40  0.40  0.40  3
> -0.35  0.35  0.35  4
> -0.30  0.30  0.30  5
> -0.25  0.25  0.25  6
> -0.20  0.20  0.20  7
> -0.15  0.15  0.15  8
> -0.10  0.10  0.10  9
> -0.05  0.05  0.05  10
>  0.00  0.00  0.00  11
>  0.00  0.00  0.05  12
>  0.00  0.00  0.10  13
>  0.00  0.00  0.15  14
>  0.00  0.00  0.20  15
>  0.00  0.00  0.25  16
>  0.00  0.00  0.30  17
>  0.00  0.00  0.35  18
>  0.00  0.00  0.40  19
>  0.00  0.00  0.45  20
>  0.00  0.00  0.50  21
>  0.05  0.05  0.45  22
>  0.10  0.10  0.40  23
>  0.15  0.15  0.35  24
>  0.20  0.20  0.30  25
>  0.25  0.25  0.25  26
>  0.20  0.30  0.20  27
>  0.15  0.35  0.15  28
>  0.10  0.40  0.10  29
>  0.05  0.45  0.05  30
>  0.0   0.50  0.0   31
> 
> input of bands.x
>  &inputpp
>     prefix  = 'BaNiAs'
>     outdir = '/disk2/xgwan/tmp/'
>     filband = 'bands.dat'
>  /
>  input of plotband.x
> bands.dat
> 2 17
> bands.xmgr
> bands.ps
> 10.5264
> 1.0 10.5264
> 
> With these inputs I could not get the same band structure as the paper
> did.I am appreciate for any suggustion and comments.
> Please tell me where I was wrong or which detail I ignored.
> 
> Have a nice day.
> 
> Deng Pan
> Nanjing Unversity
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> 

-- 


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| Gabriele Sclauzero, PhD Student                  |
| c/o:   SISSA & CNR-INFM Democritos,              |
|        via Beirut 2-4, 34014 Trieste (Italy)     |
| email: sclauzer at sissa.it                         |
| phone: +39 040 3787 511                          |
| skype: gurlonotturno                             |
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