# Band Structure Calculation with HSE06 Hybrid Functional in VASP

I am using HSE06 hybrid functional to calculate the band structure. I copied IBZKPT file as the KPOINTS file and pasted the k point path for the band structure after this file. The k point path for the band structure was obtained by another band structure calculation with PBE functional for the same system before. The new KPOINTS files is shown below.

Automatically generated mesh
61
Reciprocal lattice
0.00000000000000 0.00000000000000 0.00000000000000 1
0.09090909090909 0.00000000000000 0.00000000000000 2
...
-0.09090909090909 0.45454545454546 0.00000000000000 2
0.00000000 0.00000000 0.00000000 0.000
...
0.50000000 0.50000000 0.00000000 0.000


The INCAR file is shown below.

ISTART = 1
LWAVE = .FALSE.
LCHARGE = .TRUE.
ICHARG = 11
IVDW = 12
ISPIN = 2
MAGMOM = 0.156 -0.155 -0.096 0.096 -0.156 0.155 -0.156 0.155 0.096\
-0.096 0.156 -0.155 -0.156 0.155 0.096 -0.096 0.156 -0.155\
0.156 -0.155 -0.096 0.096 -0.156 0.155
LORBIT = 11
ENCUT = 500
ISMEAR = 0
SIGMA = 0.03
PREC = Accurate
LHFCALC = .TRUE.
AEXX = 0.25
HFSCREEN = 0.2
ALGO = Damped
TIME = 0.4
PRECFOCK = Fast
ISYM = 3
LREAL = Auto
NELMIN = 5
NELM = 700
NELMDL = -10
EDIFF = 1e-5
NPAR = 32
KPAR= 16


After the NSCF calculation done, the band structure is completely wrong. I upload the band structure below, which I obtained through using p4v software to read vasprun.xml file from the non-self consistent calculation with the HSE06 hybrid functional.

The output file shows the warning information below.

| |
| W W AA RRRRR N N II N N GGGG !!! |
| W W A A R R NN N II NN N G G !!! |
| W W A A R R N N N II N N N G !!! |
| W WW W AAAAAA RRRRR N N N II N N N G GGG ! |
| WW WW A A R R N NN II N NN G G |
| W W A A R R N N II N N GGGG !!! |
| |
| Your generating k-point grid is not commensurate to the symmetry |
| of the lattice. This can cause slow convergence with respect |
| to k-points for HF type calculations |
| suggested SOLUTIONS: |
| ) if not already the case, use automatic k-point generation |
| ) shift your grid to Gamma (G) (e.g. required for hex or fcc lattice) |
| |
-----------------------------------------------------------------------------


I am doing the band structure calculation and I have to set up the k point path manually. I cannot use automatic k-point generation, which is used in single point calculation so I do not understand what VASP means by use automatic k-point generation in this band structure calculation step.

Would anyone please give me some suggestions on the solution?

Thank you very much.

Kieran

• Can you explain what do you mean by "completely wrong"? Sep 26 at 9:35
• It seems you may have accidentally made a second account. If you want to merge these, follow the instructions from the help page: mattermodeling.stackexchange.com/help/merging-accounts
– Tyberius
Sep 27 at 3:02

As the error indicate:

| Your generating k-point grid is not commensurate to the symmetry |
| of the lattice. This can cause slow convergence with respect |
| to k-points for HF type calculations |
| suggested SOLUTIONS: |
| ) if not already the case, use automatic k-point generation |
| ) shift your grid to Gamma (G) (e.g. required for hex or fcc lattice) |


You need to define/use a correct k-point path.

As you already state that you can not use automatic k-point generation, the solution is:

• Identify the crystal symmetry you are working on.
• Look for the Brillouin zones of that symmetry.
• Select the high symmetry points for the path.
• Generate the k-point between each symmetry points.