[Pw_forum] Phonon Dispersion with LO-TO splitting

[Eyvaz Isaev]

Dear Srijan,

Z* and \epsilon, therefore, LO-TO splitting  are  for semiconductors/insulators. 

As you know, all valence bands are occupied, and conductivity bands are empty. 
Thus,
you can omit the smearing keyword to let  pw.x know that you deal with a 
semiconductor.
Then you will got dyn1-file  with Z* and \epsion, q2r.x and matdyn.x will take 
care about these 

parameters and LO-TO splitting.

Having IFC (*.fc) file you can edit Z* and  \epsilon.

See example06  and /Doc/PH.txt.

 
Best regards,
Eyvaz.
P.S. So, they are not related with postprocessing
-------------------------------------------------------------------
Prof. Eyvaz Isaev, 
Department of Physics, Chemistry, and Biology (IFM), Linkoping University, 
Sweden 

Theoretical Physics Department, Moscow State Institute of Steel & Alloys, 
Russia, 

isaev at ifm.liu.se, eyvaz_isaev at yahoo.com




________________________________
From: Srijan Kumar Saha <srijan.india at gmail.com>
To: PWSCF Forum <pw_forum at pwscf.org>
Sent: Mon, March 14, 2011 2:35:00 PM
Subject: [Pw_forum] Phonon Dispersion with LO-TO splitting


Dear QE USERS,

The QE code takes note of the presence of Z* and epsilon in the  dynamical 
matrix file 

and will add to the  dynamical matrix the  non-analytic part corresponding to 
the 

given q=>0. The 3-fold  degenerate optical modes are now split by the LO-TO 
splitting.

Here, I would like to know, whether during POST-PROCESSING, is it possible to 
manually add the 

values of the Born-effective charge and dielectric constant (which has been 
taken from the Experiments 

and not the computed ones) in the   "dynamical matrix file" so that after 
POST-PROCESSING one can get 

a phonon dispersion curve taking into account the experimental values of the Z* 
and  Dielectric constant ? 

If yes, then in which file and where, one should add the Z* and Dielectric 
constant manually ?

Looking forward to your kind reply.

Thanking you and with my best regards,

Srijan Kumar 
R&D Assistant 
JNCASR
Bangalore 560064  



      
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