band-structure calculation using GWA

Message

motonaka · #1 Post by **motonaka** » Thu May 28, 2009 6:20 am

Hello,

I have been trying band-structure calculation of silicon using GWA on VASP 5.2.
As a first step, the calculation was executed by the following settings.
[POSCAR]
cubic diamond
5.43
0.0 0.5 0.5
0.5 0.0 0.5
0.5 0.5 0.0
2
Direct
-0.125 -0.125 -0.125
0.125 0.125 0.125
[INCAR]
general:
System = diamond Si
NBANDS = 96
ISMEAR = 0 ; SIGMA = 0.05
LORBIT = 11
NEDOS = 6000
LOPTICS = .TRUE.
[KPOINTS]
Automatic mesh
0
Auto
24

As the next step, I added "ALGO = GW0 ; NOMEGA = 50" in the INCAR file, and performed GWA calculation.
As the final step, I added "ICHARG = 11" in the INCAR file, changed the KPOINT file, and executed a non-selfconsistent calculation.
[KPOINTS]
kpoints for bandstructure
4
line
reciprocal
0.00000 0.00000 0.00000 1
0.50000 0.50000 0.50000 1

Then, following messages were displayed and the calculation ended.
| 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 |

I wonder if anyone can find what is wrong with my calculation.
Thank you very much.

motonaka

semiluo · #2 Post by **semiluo** » Fri Jul 10, 2009 5:19 am

It is a warning message. I wondering VASP 5 can do such band structure calcuation with GWA, because VASP only stores WAVEFUNCTIONS and eigenvalues, no green functions. Usually, Mark Van Schilfgaarde do band structure calculation on fly after self-consisten GW calcualtion. In principle, VASP also can do that.

irene · #3 Post by **irene** » Thu Jul 30, 2009 9:05 am

I don't think it does, but I'm not sure.
I find this is indeed an interesting question and some of the experts should comment on that.

giacomo giorgi · #4 Post by **giacomo giorgi** » Wed Feb 10, 2010 2:50 am

I agree with semiluo. I do not think you need to do the non self consistent calculation for the same reasons. Just check the gap on your OUTCAR file