[Pw_forum] difference from the output of dynmat.x and Phonon dyn file

[W. YU]

>> 2. When I use dynmat.x to extract normal mode eigen
>> vectors for the Gamma point, the results seems to
be
>> different from those given by the phonon output.

>dynmat.x writes the eigendisplacements (u =
v/M^{-1/2}), 
>not the eigenmodes (v)

>Paolo

Dear Paolo, from the results of my calcualtion, I
found the difference between the two outputs are not
connected by a factor of M^{-1/2}). For some modes
they are almost the same, such as modes 12. But for
others they differ a lot, such as mode 4. The subtle
difference in mode 4 may come from the accoustic sum
rule. These two modes from the two different outputs
are attached as follows:

    omega( 4) =       3.079894 [THz] =     102.734886
[cm-1]
 (  0.000000  0.000000  0.000000  0.000000  0.000000 
0.000000 ) 
 (  0.000000  0.000000 -0.671017  0.000000 -0.106563 
0.000000 ) 
 (  0.195909  0.000000  0.000000  0.000000  0.106563 
0.000000 ) 
 ( -0.195909  0.000000  0.671017  0.000000  0.000000 
0.000000 ) 
***************************************************************************
    omega( 4) =       2.991272 [THz] =      99.778750
[cm-1]
 (  0.000000   0.000000     0.000000   0.000000    
0.000000   0.000000   )
 (  0.000000   0.000000     0.314642   0.000000    
0.443209   0.000000   )
 (  0.452290   0.000000     0.000000   0.000000   
-0.443209   0.000000   )
 ( -0.452290   0.000000    -0.314642   0.000000    
0.000000   0.000000   )
===========================================================================
**************************************************************************
     omega(12) =      24.349582 [THz] =     812.220022
[cm-1]
 (  0.973708  0.000000  0.003713  0.000000  0.000000 
0.000000 ) 
 ( -0.227577  0.000000  0.000025  0.000000  0.000000 
0.000000 ) 
 (  0.006581  0.000000 -0.000868  0.000000  0.000000 
0.000000 ) 
 (  0.006581  0.000000  0.000025  0.000000  0.000000 
0.000000 ) 

**************************************************************************
    omega(12) =      24.337573 [THz] =     811.819463
[cm-1]
 (  0.973665   0.000000    -0.001802   0.000000    
0.000000   0.000000   )
 ( -0.227786   0.000000    -0.000012   0.000000    
0.000000   0.000000   )
 (  0.006586   0.000000     0.000422   0.000000    
0.000000   0.000000   )
 (  0.006586   0.000000    -0.000012   0.000000    
0.000000   0.000000   )

**************************************************************************

Thanks,

W. YU

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