[Pw_forum] Displacements corresponding to -ve Phonon modes

[Bipul Rakshit]

Dear PWSCF users,

I am doing Phonon  of KO2 compound.  I find some -ve phonon modes at gamma
point.  (After applying  ASR also)
Following is the  dynamical matrix  formed by the phonon programme during
the run.
I just want to study the displacement corresponding to -ve modes. So Is it
enough to plot the eigen vectors given below corresponding to each mode.
Strange things what I feel in these eigen vectors are the 'K' is also moving
almost with the same magnitude as 'O' and there is no imaginary part of
eigen vectors though the frequencies are -ve.
kindly suggest.


    q = (    0.000000000   0.000000000   0.000000000 )

 **************************************************************************
     omega( 1) =      -1.178253 [THz] =     -39.302564 [cm-1]
 (  0.000000  0.000000  0.000000  0.000000  0.383086  0.000000 )
 (  0.000000  0.000000  0.000000  0.000000  0.386148  0.000000 )
 (  0.000000  0.000000  0.000000  0.000000  0.424830  0.000000 )
 (  0.000000  0.000000  0.000000  0.000000  0.424830  0.000000 )
 (  0.000000  0.000000  0.000000  0.000000  0.414231  0.000000 )
 (  0.000000  0.000000  0.000000  0.000000  0.414231  0.000000 )
     omega( 2) =      -1.150241 [THz] =     -38.368174 [cm-1]
 (  0.424996  0.000000 -0.085875  0.000000  0.000000  0.000000 )
 ( -0.413054  0.000000  0.083462  0.000000  0.000000  0.000000 )
 (  0.396157  0.000000 -0.080048  0.000000  0.000000  0.000000 )
 (  0.396157  0.000000 -0.080048  0.000000  0.000000  0.000000 )
 ( -0.384485  0.000000  0.077689  0.000000  0.000000  0.000000 )
 ( -0.384485  0.000000  0.077689  0.000000  0.000000  0.000000 )
     omega( 3) =      -1.150241 [THz] =     -38.368174 [cm-1]
 ( -0.085875  0.000000 -0.424996  0.000000  0.000000  0.000000 )
 (  0.083462  0.000000  0.413054  0.000000  0.000000  0.000000 )
 ( -0.080048  0.000000 -0.396157  0.000000  0.000000  0.000000 )
 ( -0.080048  0.000000 -0.396157  0.000000  0.000000  0.000000 )
 (  0.077689  0.000000  0.384485  0.000000  0.000000  0.000000 )
 (  0.077689  0.000000  0.384485  0.000000  0.000000  0.000000 )

-- 
Bipul Rakshit
Research Fellow,
S N Bose Centre for Basic Sciences,
Salt Lake,
Kolkata 700 098
India
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