I am VASP user and trying to reproduce the band structure of graphene, my methodology is as follows,
Step-1: Calculating the SCF (corresponding INCAR named as - INCAR-SCF) with 12x12x1 K-points.
Step-2: Copying the CHGCAR & CONTCAR obtained from step-1 and calculating non-SCF (INCAR-NonSCF) with 12x12x1 (Gamma) K-points.
Step-3 Copying CONTCAR, CHGCAR & WAVECAR from step-2 and calculating band structure (KPOINT-Kpoint path for Band structure) with same INCAR used for step-2
The resulting band structure ends up with the band gap (screenshot) (zero is the fermi level).
I played with different ISMEAR tags, but it doesn't gave fruitful result.
Any suggestions on this are very helpful and appreciated
Thank you
I agree with Antônio Lucas Rigotti Manesco, k-path in Brillouin zone must be correct because graphene has hexagonal system , the high symmetry point must take the following values
G 0.00 0.00 0.00
M 0.50 0.00 0.00
K -0.333 0.666 0.000
My first guess is that you k-path in Brillouin zone does not represent the high symmetry points you want. I recommend a review on that.
I agree with Antônio Lucas Rigotti Manesco, k-path in Brillouin zone must be correct because graphene has hexagonal system , the high symmetry point must take the following values
G 0.00 0.00 0.00
M 0.50 0.00 0.00
K -0.333 0.666 0.000
I agree with Hamad, I want to suggest you a very useful tool to build your KPOINTS file:
https://www.materialscloud.org/work/tools/seekpath
Hi Movva,
The k-mesh that you use can also have a big effect on the final band structure and 12x12x1 is probably too small. For a metal, it is always important to make sure your k-mesh is dense enough to properly capture the bands crossing at the Fermi energy. From past experience looked at graphene using other codes, I know you can get a small band gap if the k-mesh is not dense enough. To get the proper electronic structure for graphene, I would suggest increasing the size of your k-mesh to something much larger like 41x41x1 or even higher. It is always a good idea to run your calculation with different k-meshes anyway to make sure the calculation is well converged. Best of luck with your calculations!
Thanks for everyone !!
The problem has been solved with the corrected k-path (INCAR attached - hope would help someone)
Note that the Dirac conical intersections move out of the high-symetry points (and a gap can open) under certain kinds of strains.
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