[Pw_forum] Density of states

[jia chen]

Dear Peng,

Regarding to your first question, I don't think you can plot Fermi
surface for insulators, since there is no states at fermi level. The
second one, in my opinion, you probably don't want to shift spin down
level along because relative positions of spin up and down is
meaningful and Fermi energy is uniquely defined for the whole system.

Bests
Jia

On Fri, Sep 7, 2012 at 1:16 PM, Peng Chen <pchen at ion.chem.utk.edu> wrote:
> Dear All,
>
> I calculated the total density of states (in the attachment) for both afm
> and fm states of an insulator. I shifted the curves so that the band gap
> starts at 0 eV. In the top figure, the Fermi energy obtained from the scf
> calculation falls between the gap. So if I plot Fermi surface, can I get
> reliable result? In the bottom figure, I shifted the spin down DOS of fm
> state so that it can match with the spin down DOS of afm state. I am not
> sure if that is the right way to show the DOS difference of these two
> states.
>
> Another question is about the accuracy of calculation. In the scf
> calculation, I made the total energy converged within 0.001 Ry with related
> to the ecutwfc, degauss, kpoints...   Then I did band structure calculation.
> Can I say the error of calculated band energy is within 0.001 Ry?
>
>
>
>   Best Regards.
>         Peng
>
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-- 
Jia Chen
webpage: www.princeton.edu/~jiachen