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,
.com
From: Srijan Kumar Saha
To: PWSCF Forum
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
Dear Eyvaz,
Thanks a lot for your helpful reply.
> 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
Dear Srijan,
> Thanks a lot for your helpful reply.
You are welcome.
>However, in practice, sometime smearing keyword needs to be used for a
>complicated
>semiconductor or insulator in order get a faster scf convergence. And hence,
>it is better to identify a system is non-metal or metal by
Dear QE USERS,
I am trying to reproduce the phonon dispersion with LO-TO splitting of
graphene by using quantum espresso code.
To get LO-TO splitting, I have added epsil=.true. as well as
zeu=.true. in the input file of ph.x. and calculated the phonon modes
at q=0 (gamma point).
Then I have u
Dear Barnali,
There is no LO-TO splitting in graphene, or more precisely, it is zero.
Kind regards
--
Lorenzo Paulatto
Written on a virtual keyboard with real fingers
On 30 Nov 2017 3:59 pm, "Barnali Bhattacharya"
wrote:
Dear QE USERS,
I am trying to reproduce the phonon dispersion with LO
Dear Lorenzo Paulatto,
Thank you for your reply. But recently I have gone your Physical review
paper (PHYSICAL REVIEW B *87*, 214303 (2013)
) where you have shown phonon dispersion with LO-TO splitting for graphene
(Figure 2) in page 214303-4.
"Figure 2 shows the calculated graphene phonon disp
There is no LO-TO splitting in that paper, nor in the figure you've sent.
LO-TO splitting is a very specific effect that happens at Gamma: At Gamma
the LO and TO bands of graphene are degenerate.
You can find an explanation of LO-TO splitting in any solid state book and
a gazillion web sites, in a
-- Forwarded message --
From: Kondaiah Samudrala
Date: Tue, Dec 17, 2013 at 6:49 PM
Subject: Phonon dispersion with LO-TO splitting
To: pw_forum-owner at pwscf.org, pw_forum at pwscf.org, pw_forum-request at
pwscf.org
Dear all,
I am phonon dispersion for teragonal system to ch
