Hello Everyone,
I am trying to plot a band structure using two different codes ELK and Quantum Espresso.
Using ELK ima able to reproduce the band structure but Quantum espresso missing few bands in band structure.
I tried increasing the ecutwfc, ecutrho, kpoints, nbnd and even tried different pseudopotentials too but still not able to resolve the problem.
Both band structures are somewhat looking similar but still QE is still missing some details.
If someone can help then please guide.
The graphs are attached below.
Thanks,
Abhinav Nag
If you can guide me to get rid of this problem then please give your valubale comments.
Roberto D'Agosta
Konrad Gruszka Sanjiv K. Jha
Kamaraj Manokaran
A few questions:
1) Why ELK should be you reference?
2) Are you sure that both codes are using the same pseudo potentials and similar cutoffs?
3) Are you sure on how the high symmetry points are selected and labelled? In parts of your plots, it seems that the order of the points is reversed with respect to the ELK bands.
4) Are the structures similarly relaxed?
In general, I would try to use another set of pseudo potentials in QE and see what happens. Normally, you get plots that are quite similar if there are not problems with the pseudos or with convergence. You said you tried, but are the results within the QE calculations consistent?
Cheers,
Roberto
Once try to optimize the structure using proper potential sets and calculate the BS.
I hope this will help you.
Thanks SIr Roberto D'Agosta and Bibek Chettri .
The problem was arising because of the high symmetry points .
But finally, I was able to succeed.
Abhinav Nag Could you please put some light on the problem you had with your high symmetry points because I am having a similar problem with a band structure using two different codes. The two band structures with Quantum Espresso and another code show similar features but at different high symmetry points
Sonali Kakkar , the problem was appearing because of the K_Point block.
High symmetry directions under Crystal_b format worked from me. The problem was appearing in my case as I have mentioned tbipa_b.
For better understanding, you can do the exercise by changing this and see the results.
Abhinav Nag thanks a lot for your response. I am already using Crystal_b format and getting this problem. Any other suggestion to rectify this, might help.
@Sonali Kakkar are you sure how the high symmetry points are selected, labelled and represented? Do you remember that QE allows for those points to be introduced in different ways. You have different options: you introduce them as vectors with respect to the Brillouin zone unitary vectors or as vectors in the reciprocal space.
Roberto D'Agosta , I am not that familiar with QE, being a newbie for this software. I gave the high symmetry points as below in my calculations:
K_POINTS {crystal_b}
5
0.00000 0.00000 0.00000 20 ! GM
0.00000 0.50000 0.00000 20 ! Y
0.50000 0.50000 0.00000 20 ! M
0.50000 0.00000 0.00000 20 ! X
0.00000 0.00000 0.00000 20 ! GM
Could you please tell the mistake I am doing and also give some detail about the other options ?? Thanks for your earlier reply.
@Sonali I don't see any mistake in that part of your input file. Thus you should probably look at my previous answer to @Abhinav to start understanding from where the difference are coming. For example, are you sure about you reference? Are the two calculations performed with similar parameters and convergence? What about pseudos? Residual atomic forces?
It could probably help if you can upload both band plots.
I hope this helps,
Roberto
Roberto D'Agosta thanks for the response. I will surely look into the other parameters I am using for the two calculations.
I have similar problems, I am reproducing the bands using the same input and same pseudopotentials, the material is semiconductor and the fermi level dense with bands, i checked the units where it was a problem in some clusters might produce energies with hartrees or reydberg.
I dont know what my problem comes from
Maram ali amhed In my case it was because of the high symmetry points. You may check the same for your case.
@Maram, do you mind sharing your input files? Otherwise answering is more difficult.
Regards
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