[Pw_forum] requesting references for dielectric constant

[Khalid Ibne Masood Khalid]

Dear Sir,
Thank you very much for your kind reply.

On Tue, Aug 11, 2015 at 3:47 PM, stefano de gironcoli <degironc at sissa.it>
wrote:

> the dielectric constant computed by phonon is the static (high-frequency)
> dielectric constant of the system (also referred as \epsilon_\infty in the
> literature). One need to combine it with phonon results in order to compute
> \epsilon_0, the real static dielectric constant including also ionic
> polarization. It is a GS property and its computation is exact (as much or
> as little as your xc functional is  :-)  ).
>
> As for epsilon... the code says
> ! Compute the complex macroscopic dielectric function,
> ! at the RPA level, neglecting local field effects.
> ! Eps is computed both on the real or immaginary axis
> !
> so RPA (i.e. no xc contributions to the response), no local fields (i.e.
> only diagonal screening) but frequency dependence
>
> computed from an explicit summation of dipole matrix elements and
> transition energies.
>
> stefano
>
> On 11/08/2015 11:24, Khalid Ibne Masood Khalid wrote:
>
> Dear Researchers,
> I apologize that this might not be related to the code, but it would be
> very kind of you to help me in this regard. I was wondering what is the
> difference between the dielectric constant calculated from epsilon.x and
> the dielectric constant calculated from ph.x ? Is it like that epsilon.x
> calculates the dielectric constant due to electrons alone? I would also
> appreciate if you could suggest some basic references regarding epsilon.x
>
> Thank you.
>
> Khalid
> M.Sc student
> BUET
>
>
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