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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