[Pw_forum] Charged system relaxation

[degironc]

Dear Joydeep,
nelec is indeed the right variable to set if you want a charged system.
It should be set to the total number of electrons of the charged system.
nbnd should be chosen large enough that (taking into account possible
magnetization of the system)  all electrons can be accomodated in the
computed bands.
If you run pw.x with verbosity='high' when convergence is reached it
should write the bands energies and their occupations... It should be
easy to verify if the results is what you expect.
stefano


Joydeep Bhattacharjee wrote:

> Hi
>
> I want to do a structural relaxation of  a charged cluster using pwscf.
> I guess the relevant input variable is nelec.
> I am slightly confused about what happens when I use the metallic 
> options:
> occupations='smearing', smearing='methfessel-paxton', degauss=0.004, 
> for example.
> With the metallic options and nelec= nbnd*2 + #, where nbnd = (number 
> of valence bands)
> and # is the number of extra electrons I want to include, the Fermi 
> energy seems to indicate
> that the number electrons corresponding to the occupied states is 
> still the same as in the
> neutral system, ie nbnd*2.
> So how does the code account for the extra charge while calculating 
> the ground state density?
> And, if I want to infer about binding energies from such calculations, 
> what kind of corrections
> I should look for to account for the compensating jellium background.
> Also, I will be glad to learn some extra tricks related to fast scf 
> convergence in such scenarios.
> Thanks in advance.
>
> Joydeep
> JNCASR, Bangalore
>
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