[Pw_forum] negatives frequencies phonon calculation

[Ari P Seitsonen]

Dear Halima,

   Well, then something else is wrong... Can you please send you input 
files?

     Greetings,

        apsi

-=*=-=*=-=*=-=*=-=*=-=*=-=*=-=*=-=*=-=*=-=*=-=*=-=*=-=*=-=*=-=*=-=*=-=*=-=*=-
   Ari Paavo Seitsonen / Ari.P.Seitsonen at iki.fi / http://www.iki.fi/~apsi/
   Institut für Chemie der Universität Zürich, CH-8057 Zürich
   Tel: +41 44 63 54 497  /  Mobile: +41 79 71 90 935

On Thu, 8 May 2014, Halima Zaari wrote:

> 
> I already optimized the geometry and lattice constants. i get the following
> value   
> 
>  Diagonalizing the dynamical matrix
> 
>      q = (    0.000000000   0.000000000   0.000000000 )
> 
>  **************************************************************************
> 
>      omega( 1) =     -18.907308 [THz] =    -630.679895 [cm-1]
>      omega( 2) =     -18.907308 [THz] =    -630.679895 [cm-1]
>      omega( 3) =     -18.907308 [THz] =    -630.679895 [cm-1]
>      omega( 4) =     -13.087809 [THz] =    -436.562323 [cm-1]
>      omega( 5) =     -13.087809 [THz] =    -436.562323 [cm-1]
>      omega( 6) =       2.252439 [THz] =      75.133272 [cm-1]
> 
> 
> 
> 2014-05-08 11:29 GMT+01:00 Ari P Seitsonen <Ari.P.Seitsonen at iki.fi>:
>
>       Dear Halima,
>
>         (This is probably an FAQ) Did you carefully optimise the
>       geometry and lattice constants before calculating the phonons?
>       Are the imaginary frequencies small, maximum three of them and
>       only at Gamma point? This would be "normal".
>
>           Greetings from Zurich,
>
>              apsi
> 
> -=*=-=*=-=*=-=*=-=*=-=*=-=*=-=*=-=*=-=*=-=*=-=*=-=*=-=*=-=*=-=*=-=*=-=*=-=*
>       =-
>         Ari Paavo Seitsonen / Ari.P.Seitsonen at iki.fi /
>       http://www.iki.fi/~apsi/
>         Institut für Chemie der Universität Zürich, CH-8057 Zürich
>         Tel: +41 44 63 54 497  /  Mobile: +41 79 71 90 935
> 
>
>       On Thu, 8 May 2014, Halima Zaari wrote:
>
>       Dear Espresso users
>       I have performed a phonon calculation of an oxides on
>       2x2x2 q grid.   I am
>       using pw.x , ph.x; q2r.x, matdyn.x and lambda.x  to
>       calculate the 
>        phonon-electron coupling  
>       . However I am getting" NAN" in the file lambda.dat and
>       negative frequencies
>       in the electron-phonon.out 
>       i can't explain why i get negatives frequencies
>       Kindly suggest me the possible ways where I can solve
>       this.
>       cordially
>
>       --
> H.ZAARIPhD Student in laboratory of magnetism and physics of
> high energy
> Faculty of Sciences in Rabat - Morocco
> Email: halimazaari at gmail.com
> 
> 
> 
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> 
> 
> 
> --
> H.ZAARI PhD Student in laboratory of magnetism and physics of high energy
> Faculty of Sciences in Rabat - Morocco
> Email: halimazaari at gmail.com
> 
> 
>