[Pw_forum] Charged system relaxation

[Joydeep Bhattacharjee]

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