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
cheers Layla 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 > > > -- > H.ZAARI > > *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>* > > > _______________________________________________ > Pw_forum mailing list > Pw_forum at pwscf.org > http://pwscf.org/mailman/listinfo/pw_forum > -------------- next part -------------- An HTML attachment was scrubbed... URL: http://pwscf.org/pipermail/pw_forum/attachments/20140721/ecdae96b/attachment.html
