# [Pw_forum] the high symmetry line of BCT phonon dispersion band structures

Reza Behjatmanesh-Ardakani reza_b_m_a at yahoo.com
Thu Dec 18 14:53:01 CET 2014

```Hi
Maybe this discussion is useful for you:

http://qe-forge.org/pipermail/pw_forum/2014-May/104308.html

With the Best Regards

Reza Behjatmanesh-Ardakani
Associate Professor of Physical Chemistry
Department of Chemistry,
School of Science,
Payame Noor University (PNU),
Ardakan,
Yazd,
Iran.
E-mails:
1- reza_b_m_a at yahoo.com (preferred),
2- behjatmanesh at pnu.ac.ir,
3- reza.b.m.a at gmail.com.

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On Tue, 12/16/14, Kondaiah Samudrala <konda.physics at gmail.com> wrote:

Subject: Re: [Pw_forum] the high symmetry line of BCT phonon dispersion band	structures
To: pw_forum at pwscf.org
Date: Tuesday, December 16, 2014, 2:05 AM

Dear
Prof. Ari Paavo
Seitsonen
Thank you very much.. I will look
on that
with
regardsS.
AppalakondaiahPhD StudentUniversity of

On Tue, Dec 16, 2014 at
1:22 AM, Kondaiah Samudrala <konda.physics at gmail.com>
wrote:Dear all,
I am still confused with notation of
Ibrav=7 in pwscf. The IBRV=7  primitive cell vectors in
pwscf are quite different from any other. See below for two
cases of primitive vectors
IBRAV=7Case1For. e.g. In pwscf
primitive vectors of IBRV=7 are
crystal axes: (cart. coord. in units of a)
a(1) = (   0.500000  -0.500000   c/a)
a(2) = (   0.500000
0.500000   c/a )                 a(3) =
(  -0.500000  -0.500000   c/a )
Case 2On the other
hand, generally people used as (from published
papers)     crystal axes: (cart. coord. in
units of a)

a(1) = (  -0.500000  0.500000    c/a)
a(2) = (   0.500000
-0.500000   c/a )                 a(3)
= (   0.500000   0.500000   -c/a )
.
This
variation leads to changes in reciprocal vectors and then
IBZ path. From Wikipedia (http://www.sciencedirect.com/science/article/pii/S0927025610002697)
and http://www.cryst.ehu.es/
, I obtained the IBZ path for case 2.  But, what
about the IBZ path of case 1 primitive cell
vectors??  Is both are same ??? But Xcrysden showing
something else than regular Gamma, Z, Sigma, P and N points
.
I feel puzzled, would some one give
appreciatedwith regardsS. Appalakondaiah
PhD StudentUniversity of

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