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

[Reza Behjatmanesh-Ardakani]

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
   Address:
   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.

--------------------------------------------
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
 Hyderabad
 
 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
 some idea about this? any help will be
 appreciatedwith regardsS. Appalakondaiah
 PhD StudentUniversity of
 Hyderabad
 
 
 
 
 
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