[Pw_forum] about Fermi Energy shift in periodic (q=0) perturbations

[Stefano de Gironcoli]

dear Ezad Shojaee,
At any q/=0 the perturbation is such that the number of electrons does 
not change.
Even in the limit of q->0 the macroscopic term in the density response 
is zero (because in a metal
the dielectic constant is infinite).
Now consider the case of a periodic (q=0) perturbation, the simplest 
one, a constant, threated with or w/o the FE shift... which of the two 
treatments corresponds to the result you would obtain in the liimit  q->0 ?

please provide your affiliation

Stefano de Gironcoli - SISSA and DEMOCRITOS



Ezad Shojaee wrote:
> Hi
> can anyone refer me to some speciefic references about how and 
> why perodic perturbations(q=0) shift Fermi Energy in metals(in detail)?
> Thanx 
>
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