weird ordering of band-energies
Posted: Wed Jan 23, 2013 3:08 pm
Dear VASP Admin and usrs,
I am using VASP 5.2.12 serial version. I am trying to calculate energies of a 98 atom graphene sheet + 2vacancies. Structures is correct. But there is serious convergence problem with this calculation. Also for spin-polarized calculation I am taking NBAND=224. But at the end of each ionic step it gives
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 highest band is occupied at some k-points! Unless you are |
| performing a calculation for an insulator or semiconductor, without |
| unoccupied bands, you have included TOO FEW BANDS!! Please increase |
| the parameter NBANDS in file INCAR to ensure that the highest band |
| is unoccupied at all k-points. It is always recommended to |
| include a few unoccupied bands to accelerate the convergence of |
| molecular dynamics runs (even for insulators or semiconductors). |
| Because the presence of unoccupied bands improves wavefunction |
| prediction, and helps to suppress 'band-crossings.'
In the OUTCAR:
152 1.5795 0.00000
153 0.9747 0.00000
154 -0.9806 0.00000
155 1.0746 0.00000
156 0.9002 0.00000
157 -0.0583 0.00000
158 -0.7885 0.00000
159 0.0631 0.00000
160 -1.3300 0.00000
161 -0.0555 0.00000
162 -0.2893 0.00000
163 -1.0194 0.00000
164 -1.4375 0.00000
165 -5.6027 2.00000
k-point 9 : 0.3333 0.2000 0.0000
band No. band energies occupation
1 -22.1693 2.00000
2 -21.8664 2.00000
3 -21.1214 2.00000
4 -20.8307 2.00000
5 -20.7832 2.00000
6 -20.4924 2.00000
7 -20.1425 2.00000
8 -20.7430 2.00000
9 -19.9073 2.00000
10 -20.2120 2.00000
11 -19.3532 2.00000
12 -19.6897 2.00000
13 -18.5980 2.00000
14 -18.7898 2.00000
One can see the ordering of band-energies. Although there are sufficient numbers of empty bands.
If someone can help me out. It's very serious issue. As nobody has reported this kind of problem, I can assume it's not due to some bug. But is it because I'm using serial version?
Any solution? Any suggestion??
best regards,
PS
I am using VASP 5.2.12 serial version. I am trying to calculate energies of a 98 atom graphene sheet + 2vacancies. Structures is correct. But there is serious convergence problem with this calculation. Also for spin-polarized calculation I am taking NBAND=224. But at the end of each ionic step it gives
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 highest band is occupied at some k-points! Unless you are |
| performing a calculation for an insulator or semiconductor, without |
| unoccupied bands, you have included TOO FEW BANDS!! Please increase |
| the parameter NBANDS in file INCAR to ensure that the highest band |
| is unoccupied at all k-points. It is always recommended to |
| include a few unoccupied bands to accelerate the convergence of |
| molecular dynamics runs (even for insulators or semiconductors). |
| Because the presence of unoccupied bands improves wavefunction |
| prediction, and helps to suppress 'band-crossings.'
In the OUTCAR:
152 1.5795 0.00000
153 0.9747 0.00000
154 -0.9806 0.00000
155 1.0746 0.00000
156 0.9002 0.00000
157 -0.0583 0.00000
158 -0.7885 0.00000
159 0.0631 0.00000
160 -1.3300 0.00000
161 -0.0555 0.00000
162 -0.2893 0.00000
163 -1.0194 0.00000
164 -1.4375 0.00000
165 -5.6027 2.00000
k-point 9 : 0.3333 0.2000 0.0000
band No. band energies occupation
1 -22.1693 2.00000
2 -21.8664 2.00000
3 -21.1214 2.00000
4 -20.8307 2.00000
5 -20.7832 2.00000
6 -20.4924 2.00000
7 -20.1425 2.00000
8 -20.7430 2.00000
9 -19.9073 2.00000
10 -20.2120 2.00000
11 -19.3532 2.00000
12 -19.6897 2.00000
13 -18.5980 2.00000
14 -18.7898 2.00000
One can see the ordering of band-energies. Although there are sufficient numbers of empty bands.
If someone can help me out. It's very serious issue. As nobody has reported this kind of problem, I can assume it's not due to some bug. But is it because I'm using serial version?
Any solution? Any suggestion??
best regards,
PS