[Pw_forum] About nelec and tot_charge again

[陳 少華]

Dear Paolo and other forum's members,

I heard there is a method call "Rigid Band
Approximation"(RBA). In order to shift Fermi level to
conduction band or valence band in semiconductor, does
it make sense just set "nelec" parameter only ?

max
PhD candidate
Physics department, National Taiwan University,
Taiwan.

--- Paolo Giannozzi <giannozz at nest.sns.it> 說：

> On Monday 24 December 2007 12:11, oulihui666 wrote:
> 
> > I intend to ask wheather I could add a extra
> electron and +1 charge
> > simultaneously?
> 
> you can add an extra electron by setting variable
> "nelec" to the desired
> charges. The code will automatically add a
> neutralizing background (it
> must! the energy of a charged supercell is
> infinite). In practice, the energy
> is calculated as usual, but the divergent terms will
> be calculated as if 
> the system was neutral. For a molecule the energy so
> obtained will 
> converge for increasing size of the supercell to the
> true energy of the
> charged molecule; there are various tricks to
> speedup the convergence
> (e.g. the Makov-Payne correction). Formation
> energies of charged defects
> can also be calculated but it is a more tricky
> business.
> 
> By the way, all this has been explained 2n+1 times.
> 
> Paolo
> -- 
> Paolo Giannozzi, Democritos and Udine University 
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