Hi Xu Huang,

   All I know is there is a similar question to this on the forum asked 
recently: Lorenzo Paulatto answered the following:


Hello, in density function perturbation theory, contrary to finite-differenes
method, there is no atom displacement: quantum-mechanics perturbation theory
is used.

See this reference: 
<<https://outlook.office.com/owa/?realm=leeds.ac.uk&path=/mail/search>http://journals.aps.org/rmp/abstract/10.1103/RevModPhys.
73.515> for details on the method how it is implemented in QE.

Tis lecture from Stefano Baroni to get a quick idea: < https://
www.dropbox.com/s/xi06fv6oz07j9du/EUSPec%202016%20%281%29.pdf?dl=0<http://www.dropbox.com/s/xi06fv6oz07j9du/EUSPec%202016%20%281%29.pdf?dl=0>>


So there is likely nothing wrong with the axsf file. For your second question 
however I am not sure how to animate, unless you do it manually using the force 
vector directions?


Regards,

Louis

________________________________
From: pw_forum-boun...@pwscf.org <pw_forum-boun...@pwscf.org> on behalf of 
Huang, Xu <xu-hu...@uiowa.edu>
Sent: 27 March 2017 05:40:51
To: pw_forum@pwscf.org
Subject: [Pw_forum] Phonon axsf does not move in XCrysden


Dear all,


I'm using QE-5.2.0 to do the phonon calculation to test some small gas 
molecules, such as O2, CH4 etc.

I got a "dynmat.axsf" for O2 with 6 modes shown below.

However, when I type "xcrysden --axsf dynmat.axsf" to visualize the vibrational 
mode,

I can't see any movement when I click the <- and -> arrows back and forth.

(I do see the arrows of forces when display them.)

Is there anything wrong with this axsf file?

Or is there any parameter for the dynmat.x to produce specific axsf to animate 
a certain mode?


Thank you,

Xu Huang


-----------------------------------------------------

ANIMSTEPS   6
CRYSTAL
PRIMVEC
   21.167088344    0.000000000    0.000000000
    0.000000000   21.167088344    0.000000000
    0.000000000    0.000000000   21.167088344
PRIMCOORD  1
      2   1
   O      1.23655   0.00000   0.00000   0.00000  -0.00000  -0.07722
   O      0.00000   0.00000   0.00000   0.00000   0.00000   0.06354
PRIMCOORD  2
      2   1
   O      1.23655   0.00000   0.00000   0.00000  -0.07071  -0.00000
   O      0.00000   0.00000   0.00000   0.00000   0.07071  -0.00000
PRIMCOORD  3
      2   1
   O      1.23655   0.00000   0.00000   0.00000  -0.00000   0.06354
   O      0.00000   0.00000   0.00000   0.00000   0.00000   0.07722
PRIMCOORD  4
      2   1
   O      1.23655   0.00000   0.00000  -0.07071  -0.00000   0.00000
   O      0.00000   0.00000   0.00000  -0.07071   0.00000   0.00000
PRIMCOORD  5
      2   1
   O      1.23655   0.00000   0.00000   0.00000  -0.07071  -0.00000
   O      0.00000   0.00000   0.00000   0.00000  -0.07071  -0.00000
PRIMCOORD  6
      2   1
   O      1.23655   0.00000   0.00000  -0.07071   0.00000   0.00000
   O      0.00000   0.00000   0.00000   0.07071   0.00000   0.00000


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