[Wien] FER: Fermi level position problem

[Yushan Wang]

 Dear uers,
 for pure anatase TiO2, the fermi level is just above the valence band,
but
when I use a nitrogen atom to replace one oxygen atom, I find the fermi
level down into the valence band. during my calculation for the two system
above. nothing was changed. so who know why for the fermi level's shift?

yushan



On Wed, 5 Nov 2003, Peter Blaha wrote:

> >  I am calculating on different systems, but I have the same problem:
> > plotting the band structure the Fermi Level is often 0.2 - 0.4 eV lower
> > in energy (down into the Valence Band) than the expected position (after
> > have introduced the value from .scf file into .insp file). The problem
> > is for exemple in calculating graphite. I have done convergence in
> > charge with 0.0001 of convergence parameter. Is it a problem of
> > convergence? Or is it something else?
>
> I would not expect it to be a convergence problem.
>
> Either you are doing something wrong (changing XC potential, RKmax, Energy-
> parameters, different structure or lattice parameters, wrong nr.of electrons
> in case.in2,...)
>
> or you use a (crude) "shifted" k-mesh in the scf cycle (if your valence-
> band maximum (EF) is at Gamma, but Gamma is not in the scf k-mesh, then EF
> will be "lower" and when plotting a bandstructure including Gamma it
> looks as if EF is inside the valence bands.
>
> or you use a large broadening scheme ? Use TETRA
>
>                                       P.Blaha
> --------------------------------------------------------------------------
> Peter BLAHA, Inst.f. Materials Chemistry, TU Vienna, A-1060 Vienna
> Phone: +43-1-58801-15671             FAX: +43-1-58801-15698
> Email: blaha at theochem.tuwien.ac.at    WWW: http://info.tuwien.ac.at/theochem/
> --------------------------------------------------------------------------
>
> _______________________________________________
> Wien mailing list
> Wien at zeus.theochem.tuwien.ac.at
> http://zeus.theochem.tuwien.ac.at/mailman/listinfo/wien
>