[Pw_forum] problem plotting graphene band structure

[Giovanni Cantele]

I do not have the time to check the coordinates now, but I guess that the coordinates of the k points are wrong. 
If I well remember, for example, the coordinates of the M point are 1/2 (and not 1/3) a reciprocal lattice vector,
so your M point, because you choose crystal coordinates, should look like 0.5 0 0. Maybe other issues are present
for the other k points.

As a minor remark, if you are studying graphene (and not graphite), the coordinate of the A point is not needed
(band structure along a direction where you do not have a true periodicity).

Giovanni


> On 29 Nov 2016, at 13:02, Shan <ecebhushan at gmail.com> wrote:
> 
> Dear Experts,
> 
> I am beginner of QE. As part of the practice, I am extracting the basic structural and electronic properties of simple semiconducting materials, 1D and 2D structures. Things were fine untill i tried graphene. However, I stuck with graphene band structure for the last 3 days. As a beginner, I have done everything i can to resolve the problem. when i try to plot the band structure of 2 atom graphene, either i get a wrong band gap or an empty plot.
> 
> Here I am attaching the SCF code and Bandstructure code. Can someone please verify and tell me where the problem is. 
> 
> SCF code:-
> 
> &CONTROL
>   calculation='scf',
>   outdir='.',
>   prefix='pwscf',
>   pseudo_dir='.',
>   verbosity='low',
>   tprnfor=.true.,
>   tstress=.true.,
> /
> 
> &SYSTEM
>   ibrav=4,
>   celldm(1)=4.6509939378d0, celldm(3)=4.536666,
>   nat=2,
>   ntyp=1,
>   ecutwfc=30,
>   ecutrho=120,
>   input_dft='pbe',
>   occupations='smearing',
>   smearing='mv',
>   degauss=0.005d0,
> /
> 
> &ELECTRONS
>   conv_thr=1d-08,
>   mixing_beta=0.7d0,
> /
> 
> ATOMIC_SPECIES
>   C 12.010700d0 C.pbe-n-rrkjus_psl.0.1.UPF
> 
> ATOMIC_POSITIONS {crystal}
>    C   0.0000000000d0   0.0000000000d0   0.0000000000d0
>    C   0.3333333333d0   0.6666666667d0   0.0000000000d0
> 
> K_POINTS {automatic}
>   22 22 1 0 0 0
> 
> 
> Band Structure code:-
> 
> &CONTROL
>   calculation='bands',
>   outdir='.',
>   prefix='pwscf',
>   pseudo_dir='.',
>   verbosity='high',
> /
> 
> &SYSTEM
>   ibrav=4,
>   celldm(1)=4.6509939378d0, celldm(3)=4.536666,
>   nat=2,
>   ntyp=1,
>   ecutwfc=30,
>   ecutrho=120,
>   input_dft='pbe',
>   occupations='smearing',
>   smearing='mv',
>   degauss=0.005d0,
> /
> 
> &ELECTRONS
>   conv_thr=1d-08,
>   mixing_beta=0.7d0,
> /
> 
> ATOMIC_SPECIES
>   C 12.010700d0 C.pbe-n-rrkjus_psl.0.1.UPF
> 
> ATOMIC_POSITIONS {crystal}
>    C   0.0000000000d0   0.0000000000d0   0.0000000000d0
>    C   0.3333333333d0   0.6666666667d0   0.0000000000d0
> 
> K_POINTS {crystal_b}
> 5
>   0.000 0.0 0.16666667 10 ! A
>   0.000 0.000 0.0 20 ! G
>   0.33333333 0.57735027 0.0 20 ! K
>   0.33333333 0.0 0.0 20 ! M
>   0.0 0.0 0.0 0 ! G
> 
> 
> 
> Thank you very much in advance,
> 
> Regards,
> B S Bhushan
> Ph.D Scholar
> Indian Institute of Information Technology and Management, Gwalior, 
> India.
> 
> <scf.in><bs.in>_______________________________________________
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-- 

Giovanni Cantele, PhD
CNR-SPIN
c/o Dipartimento di Fisica
Universita' di Napoli "Federico II"
Complesso Universitario M. S. Angelo - Ed. 6
Via Cintia, I-80126, Napoli, Italy
e-mail: giovanni.cantele at spin.cnr.it
Phone: +39 081 676910
Skype contact: giocan74

ResearcherID: http://www.researcherid.com/rid/A-1951-2009
Web page: http://people.na.infn.it/~cantele

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