Dear All,
I am a beginner in VASP , trying to calculate band structure and DOS. While doing the same, I calculated the charge density first on automatic mesh KPOINTs, then copied CHGCAR and IBZKPT file and added KPOINTS along high symmetry lines with zero weight But i always face the following WARNING : "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)"
Also the band structure is not correct.
Could any body please help me, to get out from this. I am attaching my files herewith.
Hi,
This warning always come when we don't use automatic k-mesh generation, so no need to worry about this, it will always come in HSE calculations.
However, please make a correction to your KPOINTS file, here you have taken only this path
0.50000 0.50000 0.50000 0
0.00000 0.00000 0.00000 0
0.00000 0.00000 0.00000 0
0.00000 0.50000 0.50000 0
0.00000 0.50000 0.50000 0
0.25000 0.62500 0.62500 0
0.37500 0.7500 0.37500 0
0.00000 0.00000 0.00000 0
You should increase the step size in between the two high symmetry kpoints. You can look for the same in the OUTCAR of GGA non self consistent calculations. Like in going from (0.5,0.5,0.5) to (0,0,0), you might have given 50 points (say), that will come in your OUTCAR like the following,
0.50000000 0.50000000 0.50000000 0.007
0.48979592 0.48979592 0.48979592 0.007
0.47959184 0.47959184 0.47959184 0.007
0.46938776 0.46938776 0.46938776 0.007
0.45918367 0.45918367 0.45918367 0.007
0.44897959 0.44897959 0.44897959 0.007
0.43877551 0.43877551 0.43877551 0.007
0.42857143 0.42857143 0.42857143 0.007
0.41836735 0.41836735 0.41836735 0.007
0.40816327 0.40816327 0.40816327 0.007
0.39795918 0.39795918 0.39795918 0.007
0.38775510 0.38775510 0.38775510 0.007
0.37755102 0.37755102 0.37755102 0.007
0.36734694 0.36734694 0.36734694 0.007
0.35714286 0.35714286 0.35714286 0.007
0.34693878 0.34693878 0.34693878 0.007
0.33673469 0.33673469 0.33673469 0.007
0.32653061 0.32653061 0.32653061 0.007
0.31632653 0.31632653 0.31632653 0.007
0.30612245 0.30612245 0.30612245 0.007
0.29591837 0.29591837 0.29591837 0.007
0.28571429 0.28571429 0.28571429 0.007
0.27551020 0.27551020 0.27551020 0.007
0.26530612 0.26530612 0.26530612 0.007
0.25510204 0.25510204 0.25510204 0.007
0.24489796 0.24489796 0.24489796 0.007
0.23469388 0.23469388 0.23469388 0.007
0.22448980 0.22448980 0.22448980 0.007
0.21428571 0.21428571 0.21428571 0.007
0.20408163 0.20408163 0.20408163 0.007
0.19387755 0.19387755 0.19387755 0.007
0.18367347 0.18367347 0.18367347 0.007
0.17346939 0.17346939 0.17346939 0.007
0.16326531 0.16326531 0.16326531 0.007
0.15306122 0.15306122 0.15306122 0.007
0.14285714 0.14285714 0.14285714 0.007
0.13265306 0.13265306 0.13265306 0.007
0.12244898 0.12244898 0.12244898 0.007
0.11224490 0.11224490 0.11224490 0.007
0.10204082 0.10204082 0.10204082 0.007
0.09183673 0.09183673 0.09183673 0.007
0.08163265 0.08163265 0.08163265 0.007
0.07142857 0.07142857 0.07142857 0.007
0.06122449 0.06122449 0.06122449 0.007
0.05102041 0.05102041 0.05102041 0.007
0.04081633 0.04081633 0.04081633 0.007
0.03061224 0.03061224 0.03061224 0.007
0.02040816 0.02040816 0.02040816 0.007
0.01020408 0.01020408 0.01020408 0.007
0.00000000 0.00000000 0.00000000 0.007
Similar for other high symmetry points. This weight (0.007) you have to take as zero and rerun the calculations. I am getting where you are facing problem, but please attach your vasprun.xml file once your calculations are completed, so that i can help you.
Kindly find my KPOINTS file for reference.
Hope it helps!
Another tool that you can use to get an accurate electronic band structure and DOS, is using ELK which is a free software and TB09 as the exchange correlation functional.
B.S calculation by using HSE 06 will complete in two steps 1. HSE SCF: for this copy the input files along with CHGCAR and WAVECAR from PBE-scf. Put the HSE tags in INCAR. 2. HSE-B.S: when hse.scf is completed thn copy the four input files along with CHGCAR, WAVECAR and IBZKPTS from HSE-scf to HSE.B.S. thn go to pbe-band gap directory and open OUTCAR. search "k-points in reciprocal lattice" . Copy those KPOINTS and paste at the bottom of IBZKPTS and rename it as KPOINTS. The 4rth column of the kpoints copied from OUTCAR should be changed to 0.000.
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