[Pw_forum] epsilon.x

Layla Martin-Samos lmartinsamos at gmail.com
Mon Jul 21 12:12:19 CEST 2014

you will never have the correct experimental gap with epsilon. Epsilon
implements Random Phase Approximation dielectric response with no-local
fields effects (and of course no-excitonic effects). You need to go to
state-of-art GW caluclations + Bethe-Salpeter. Or at least some hybrid
functional. Read
Electronic excitations: density-functional versus many-body
Green’s-function approaches  Rev. Mod. Phys. *74*, 601 – Published 7 June
2002  Giovanni Onida, Lucia Reining, and Angel Rubio



2014-07-21 11:30 GMT+02:00 Halima Zaari <halimazaari at gmail.com>:

> Hello all,
> I am trying to find the optical properties of GaN which has Eg=3.4 eV
> using the epsilon.x
> i get the files containig the eloss fucntion and dielectric funtion but
> the file epsilon.out the epsilon file gives me the following information
> Fermi energy is 11.66 eV the system is a metal
> perfoming eps calculation
> the bulk xx plasomn is 12.41
> haw i can solve this problem.
> thanks in advance
> --
> *PhD Student in laboratory of magnetism and physics of high energy (LMPHE)*
> *Faculty of Sciences in Rabat - Morocco*
> *Email:** halimazaari at gmail.com <halimazaari at gmail.com>*
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