[Pw_forum] Reg: How to know the mode name and due to which atom it is happening?

Peram sreenivasa reddy peramsreenivas at gmail.com
Mon Mar 31 17:10:00 CEST 2014

Dear Pwscf,

In my phonon calculations i got one imaginary mode in gamma to X direction.
I want to know which mode it is? and due to which atom it is happening?

I checked the case.ph.out file. In this file it is given like below.

Mode symmetry, O_h (m-3m)  point group:
  omega(  1 -  3) =        -16.6  [cm-1]   --> T_1u G_15  G_4- I
  omega(  4 -  6) =        122.3  [cm-1]   --> T_1u G_15  G_4- I
  omega(  7 -  9) =        145.0  [cm-1]   --> T_2g G_25' G_5+ R
  omega( 10 - 12) =        258.5  [cm-1]   --> T_1u G_15  G_4- I

Here i am attaching the case.agr file

Here all acoustic modes are given with same frequency. How can know that
particular mode name.

 My system is X2YZ type. How can i know this imaginary mode is due to which
atom. I plotted partial phonon density of states also. But all atoms are
giving same contribution in this acoustic mode region.

 Thank you in advance.
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