[Pw_forum] Problem with the Band Structure Calculation

[Lex Kemper]

I have a passing familiarity with your system and this problem.
Comparing band structure is hard, for a number of reasons. One is an
inconsistency in the notation -- for simple tetragonal units cells, for
example, there are at least two different notations for the
high-symmetry points. Secondly, the primitive units cell for system
you're looking at is not simple tetragonal, it's body centered
tetragonal. This has a whole different set of symmetry points. Now, you
can use k-points from the conventional (tetragonal) unit cell, but the
number of bands you get will vary, depending on whether you're using the
primitive zone or the conventional one.

Good luck,

Lex Kemper
University of Florida

?? wrote:
> The structure in paper have the sysmmetry of the space group
> I4/mmm(139) with Ba 2a(0 0 0) Ni 4d (0.5 0 0.25) As (0 0 0.3476).
> and my input are:
> 
> 
>  &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
> 
> 
> Could you tell the structure I inputed are the same of that is in the
> paper.I compare with XCryden to Wien2k input of this structure,it
> seems the same.
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