effect of ISMEAR on the Fermi level during the calculation
Posted: Sun Jun 10, 2012 4:39 am
Hi All,
I am trying to obtain the VBM of SiO2 from the calculation.
First, I happened to try different ISMEAR(-5/0 with different sigma), i found that the Fermi Energy/VBM in the OUTCAR is very different.
Then I fixed the ISMEAR to -5, and changed the KPOINTS (from 3X3X3 to 21X21X21), and the result show that the total energy was convergent, but the Fermi Energy still quite different under different KPOINTS condition, and no tendency to follow.
However, as mentioned in the UG of VASP, for insulator and semiconductor, ISMEAR=-5 is recommended.
SO I would like to check with those experts that whether the Fermi Energy calculated with the ISMEAR=-5 is more adoptable?
Thanks a lot.
I am trying to obtain the VBM of SiO2 from the calculation.
First, I happened to try different ISMEAR(-5/0 with different sigma), i found that the Fermi Energy/VBM in the OUTCAR is very different.
Then I fixed the ISMEAR to -5, and changed the KPOINTS (from 3X3X3 to 21X21X21), and the result show that the total energy was convergent, but the Fermi Energy still quite different under different KPOINTS condition, and no tendency to follow.
However, as mentioned in the UG of VASP, for insulator and semiconductor, ISMEAR=-5 is recommended.
SO I would like to check with those experts that whether the Fermi Energy calculated with the ISMEAR=-5 is more adoptable?
Thanks a lot.