[Pw_forum] The atomic displacements By QE and Abinit

[Stefano Baroni]

eigenmodes for degenerate modes are only defined within a unitary transformation
normalization may also differ in different codes
codes other than those in the QE distribution may give wrong results ;-)

SB

On Apr 18, 2011, at 4:32 AM, 昶棘汐 wrote:

> Dear all
> 
> i have run the program ph.x and got the outfile  *.dyn_G. from what I understand, the diagonalized dynamical matrix should give displacements of each atom. and each column gives the real and imaginary components of the displacements .so in the output
> 
> omega( 1) =      -0.294635 [THz] =      -9.828034 [cm-1]
>  (  0.000006  0.000000 -0.000003  0.000000  0.288697  0.000000 ) 
>  (  0.000000  0.000000  0.000007  0.000000  0.288697  0.000000 ) 
>  ( -0.000006  0.000000 -0.000003  0.000000  0.288697  0.000000 ) 
>  (  0.000010  0.000000 -0.000006  0.000000  0.288654  0.000000 ) 
>  (  0.000000  0.000000  0.000011  0.000000  0.288654  0.000000 ) 
>  ( -0.000010  0.000000 -0.000006  0.000000  0.288654  0.000000 ) 
>  (  0.000006  0.000000 -0.000003  0.000000  0.288697  0.000000 ) 
>  (  0.000000  0.000000  0.000007  0.000000  0.288697  0.000000 ) 
>  ( -0.000006  0.000000 -0.000003  0.000000  0.288697  0.000000 ) 
>  (  0.000010  0.000000 -0.000006  0.000000  0.288654  0.000000 ) 
>  (  0.000000  0.000000  0.000011  0.000000  0.288654  0.000000 ) 
>  ( -0.000010  0.000000 -0.000006  0.000000  0.288654  0.000000 ) 
> 
> however it is different from the the outcome of Abinit 
> 
> Eigendisplacements 
>  (will be given, for each mode : in cartesian coordinates
>    for each atom the real part of the displacement vector,
>    then the imaginary part of the displacement vector)
>   Mode number    1   Energy    0.000000E+00
>  Attention : low frequency mode.
>    (Could be unstable or acoustic mode)
> ;  1  0.00000000E+00  0.00000000E+00 -2.05634696E-03
> ;     0.00000000E+00  0.00000000E+00  0.00000000E+00
> ;  2  0.00000000E+00  0.00000000E+00 -2.05634695E-03
> ;     0.00000000E+00  0.00000000E+00  0.00000000E+00
> ;  3  0.00000000E+00  0.00000000E+00 -2.05634695E-03
> ;     0.00000000E+00  0.00000000E+00  0.00000000E+00
> ;  4  0.00000000E+00  0.00000000E+00 -2.05634696E-03
> ;     0.00000000E+00  0.00000000E+00  0.00000000E+00
> ;  5  0.00000000E+00  0.00000000E+00 -2.05634696E-03
> ;     0.00000000E+00  0.00000000E+00  0.00000000E+00
> ;  6  0.00000000E+00  0.00000000E+00 -2.05634696E-03
> ;     0.00000000E+00  0.00000000E+00  0.00000000E+00
> ;  7  0.00000000E+00  0.00000000E+00 -2.05634696E-03
> ;     0.00000000E+00  0.00000000E+00  0.00000000E+00
> ;  8  0.00000000E+00  0.00000000E+00 -2.05634695E-03
> ;     0.00000000E+00  0.00000000E+00  0.00000000E+00
> ;  9  0.00000000E+00  0.00000000E+00 -2.05634695E-03
> ;     0.00000000E+00  0.00000000E+00  0.00000000E+00
> ; 10  0.00000000E+00  0.00000000E+00 -2.05634696E-03
> ;     0.00000000E+00  0.00000000E+00  0.00000000E+00
> ; 11  0.00000000E+00  0.00000000E+00 -2.05634696E-03
> ;     0.00000000E+00  0.00000000E+00  0.00000000E+00
> ; 12  0.00000000E+00  0.00000000E+00 -2.05634696E-03
> ;     0.00000000E+00  0.00000000E+00  0.00000000E+00
> 
> how could i understand it .why the QE and Abinit give the different outcome . i hope some help . and thanks in advance 
> 
> tanyci
> nankai university , tianjin
> china
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---
Stefano Baroni - SISSA  &  DEMOCRITOS National Simulation Center - Trieste
http://stefano.baroni.me [+39] 040 3787 406 (tel) -528 (fax) / stefanobaroni (skype)

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