[Pw_forum] Problem in phonon-5.0.2

[Paolo Giannozzi]

>From the Doc/release-notes file:
===
Fixed in 5.0.3 version:
[...]
   * PHonon: restart with convt=.true. was not working with PAW
   * PHonon: in matdyn.x, displacement patterns were no longer correct
     if eigenvectors of the dynamical matrix were also written to file
   * PHonon: compatibility with files produced by previous releases
     was broken if pools were used
   * VERY NASTY PHonon bug: symmetry Sq=-q+G introduced in v.5.0.2
     could lead to bad phonons in some cases and has been disabled 
   * PHonon: effective charges eu + PAW were not accurate with pools;
     effective charges eu + US PP + spin-orbit nonmagnetic were not
     working in parallel.

I guess the "VERY NASTY PHonon bug" is the one you encountered.
V.5.0.3 is very similar to v.5.0.2 so it shouldn't be difficult 
to adapt your codes built upon v.5.0.2

P.

On Thu, 2014-09-04 at 11:57 -0400, Lin, Yangzheng wrote:
> Dear all QE users,
>  
> Although phonon-5.1 is available now, I have to use phonon-5.0.2 for
> some other codes I am using were built on phonon-5.0.2.
>  
> Recently I found some problem that phonon-5.0.2 did not give the same
> phonon frequencies as phonon-5.1 for some q points of my system. The
> difference is big. For example,
>  
> Phonon-5.1 gave
>      q = (    0.000000000   0.000000000   0.053115094 )
>  **************************************************************************
>      freq (    1) =       3.205949 [THz] =     106.938946 [cm-1]
> but Phonon-5.0.2 gave
>      q = (    0.000000000   0.000000000   0.053115094 )
>  **************************************************************************
>      omega( 1) =      -7.856216 [THz] =    -262.055171 [cm-1]
> 
> I found some codes in phonon-5.0.2 were modified by phonon-5.1 in
> subroutine smallg_q (xq, modenum, at, bg, nrot, s, ftau, sym, minus_q)
> 
>  phonon-5.0.2 used
>      if (.not.minus_q) then
>         raq = - raq
>         minus_q = eqvect (raq, aq, zero, accep)
>      endif
> 
>  phonon-5.1 modified it as
>      if (sym(irot).and..not.minus_q) then
>         raq = - raq
>         minus_q = eqvect (raq, aq, zero, accep)
>      endif
> 
> So I did this modification in phonon-5.0.2 and the modified
> phonon-5.0.2 gave the same phonon frequencies as those from phonon-5.1
> for the same q point.
> 
> Since I have to continue use phonon-5.0.2 now, my question is does
> anyone of you know if there were some other problems found in
> phonon-5.0.2? Thanks.
> 
> Sincerely,
> Yangzheng Lin
> Postdoctoral Associate
> Geophysical Laboratory, Carnegie Institution for Science
> 5251 Broad Branch Rd. NW, Washington, DC 20015, USA
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-- 
 Paolo Giannozzi, Dept. Chemistry&Physics&Environment, 
 Univ. Udine, via delle Scienze 208, 33100 Udine, Italy
 Phone +39-0432-558216, fax +39-0432-558222