[Pw_forum] GaAs Band structure

[Duy Le]

Dear Nand,

I don't see anything wrong with your calculated band structure.

1. There is a band gap so the Fermi level should be in the middle of the
gap. If you want the dash line to locate in the middle of the gap, you could
change the reference energy correspondingly when doing plotband.x

2. The gap must be underestimated. If this gap is too wrong to trust, check
the lattice parameter.

Best,


On Thu, Aug 27, 2009 at 3:37 PM, nand <rana_nand at yahoo.com> wrote:

>
>
> Sir,
> I am a research scholar at the Ranchi university, India. It will be a great
> help if you can help me with the band structure calculation for GaAs using
> Quantum Espresso.
> I do not get the correct band structure  even with the input file you
> mentioned below. I am attaching the band structure pdf file which I produced
> using  input file given below. As you can see that the fermi level is
> wrongly located and the band gap is badly  underestimated. Please tell me
> about the possible fault(s) possible in my calculation.
> Thanking you in advance.
> Nand Rana,
> (Research Scholar)
> Ranchi, India.
>
> -----------------------------------
> input file for the scf calculation:
>
> &control
>   calculation='scf',
>
>   outdir='./tmp',
>   prefix='gaas',
>   pseudo_dir='/espresso-4.0.4/pseudo'
> /
>
> &system
>   ibrav=2,
>   celldm(1)=10.6827,
>   nbnd=8,
>   nat=2,
>   ntyp=2,
>   ecutwfc=40.0d0,
>
>   occupations='fixed',
>   nspin=1
> /
>
> &electrons
>   conv_thr=1d-6,
>   mixing_beta=0.7,
>   diagonalization='david'
> /
>
> ATOMIC_SPECIES
>  Ga   69.723   Ga.pz-bhs.UPF
>  As   74.92160 As.pz-bhs.UPF
>
> ATOMIC_POSITIONS  alat
>   Ga 0.0   0.0   0.0
>   As 0.25  0.25  0.25
>
> K_POINTS   automatic
>    10 10 10 0 0 0
>
>
>
>
>
>
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>


-- 
--------------------------------------------------
Duy Le
PhD Student
Department of Physics
University of Central Florida.
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