[Pw_forum] ph.x: Wrong classes for C_3v

[David Strubbe]

Andrea and Giovanni,

Thank you for your comments. Yes, it was a mistake to have this subtle
difference between the lattice vectors. I changed them to be identical:

CELL_PARAMETERS
5.42763 0.0 0.0
0.0 5.42763 0.0
0.0 0.0 5.42763

Now pw.x can run in high verbosity without crashing, and the phonon run
proceeds, but there is clearly still a symmetry problem as it gives '?' for
many of the modes in the symmetry analysis.

     Mode symmetry, C_3v (3m)   point group:

     omega(  1 -  1) =       -336.3  [cm-1]   -->   ?
     omega(  2 -  2) =       -336.3  [cm-1]   -->   ?
     omega(  3 -  3) =       -336.3  [cm-1]   -->   ?
     omega(  4 -  4) =       -336.3  [cm-1]   -->   ?
     omega(  5 -  5) =       -336.3  [cm-1]   -->   ?
     omega(  6 -  6) =       -336.3  [cm-1]   -->   ?
     omega(  7 -  7) =         26.1  [cm-1]   -->   ?
     omega(  8 -  8) =         26.2  [cm-1]   -->   ?
     omega(  9 -  9) =         26.2  [cm-1]   -->   ?
     omega( 10 - 10) =        286.6  [cm-1]   -->   ?
     omega( 11 - 11) =        286.6  [cm-1]   -->   ?
     omega( 12 - 12) =        287.0  [cm-1]   -->   ?
     omega( 13 - 13) =        287.1  [cm-1]   -->   ?
     omega( 14 - 14) =        287.5  [cm-1]   -->   ?
     omega( 15 - 15) =        288.1  [cm-1]   -->   ?
     omega( 16 - 16) =        413.2  [cm-1]   --> A_1  L_1        I+R
     omega( 17 - 17) =        413.2  [cm-1]   --> A_2  L_2
     omega( 18 - 19) =        413.2  [cm-1]   --> E    L_3        I+R
     omega( 20 - 21) =        413.3  [cm-1]   --> E    L_3        I+R
     omega( 22 - 22) =        583.3  [cm-1]   --> A_1  L_1        I+R
     omega( 23 - 24) =        583.3  [cm-1]   --> E    L_3        I+R


David Strubbe
MIT


On Wed, Jan 16, 2013 at 2:10 AM, Dal Corso Andrea <dalcorso at sissa.it> wrote:

> On Tue, 2013-01-15 at 18:10 -0500, David Strubbe wrote:
> > Dear QE developers,
> >
> >
> > I have encountered an internal error regarding symmetry with QE 5.0.2,
> > for a calculation with 8 atoms of Si. The scf calculation with pw.x
> > runs fine, but then ph.x crashes immediately with the following
> > message. This happened in serial and parallel with ifort, as well as
> > in serial with gfortran. Input files scf.in and ph.in are below also.
> > I tried with the patch to 5.0.3 emailed out by Dr. Gianozzi a few
> > weeks, and got the same error.
> >
> >
> > David Strubbe
> > MIT
> >
> >
> >  %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
> > %%%%%%%%%
> >      Error in routine divide_class (1):
> >      Wrong classes for C_3v
> >  %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
> > %%%%%%%%%
> >
> >
> > $ cat scf.in
> > &control
> >    prefix = 'silicon'
> >    calculation = 'scf'
> >    restart_mode = 'from_scratch'
> >    pseudo_dir = '/home/dstrubbe/raman_Si/pseudo'
> > /
> > &system
> >    ibrav = 0
> >    celldm(1) = 1.88972613
> >    nat = 8
> >    ntyp = 1
> >    nbnd = 32
> >    ecutwfc = 50.0
> > /
> > &electrons
> > /
> > CELL_PARAMETERS
> > 5.427632 0.0 0.0
> > 0.0 5.42763 0.0
> > 0.0 0.0 5.42763
>
>
> This is a well known problem. pw.x finds more symmetries than the
> routines that analyze the point group. This happens because the
> difference between 5.427632 and 5.42763 is too small and pw.x finds
> symmetries that are not there. If this is a mistake in your input than
> please correct it an use three equal values, if instead this is really
> what you want, than the threshold for comparing symmetries (accept
> parameter in symm_base module) should be decreased, otherwise pw.x
> ignore the difference in any case.
>
>
> HTH,
>
> Andrea
>
>
>
>
>
> > ATOMIC_SPECIES
> >   Si  28.086  Si.UPF
> > ATOMIC_POSITIONS angstrom
> > Si     0.542763    0.542763    0.542763
> > Si     3.256579    3.256579    0.542763
> > Si     0.542763    3.256579    3.256579
> > Si     3.256579    0.542763    3.256579
> > Si     1.899671    1.899671    1.899671
> > Si     4.613487    4.613487    1.899671
> > Si     1.899671    4.613487    4.613487
> > Si     4.613487    1.899671    4.613487
> > K_POINTS automatic
> > 1 1 1 0 0 0
> >
> >
> > $ cat ph.in
> > phonons of Si at Gamma
> >  &inputph
> >   tr2_ph=1.0d-12,
> >   prefix='silicon',
> >   epsil=.true.,
> >   trans=.true.,
> >   amass(1)=28.0855,
> >  /
> > 0.0 0.0 0.0
> >
> >
> > _______________________________________________
> > Pw_forum mailing list
> > Pw_forum at pwscf.org
> > http://pwscf.org/mailman/listinfo/pw_forum
>
>
> _______________________________________________
> Pw_forum mailing list
> Pw_forum at pwscf.org
> http://pwscf.org/mailman/listinfo/pw_forum
>
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.quantum-espresso.org/pipermail/users/attachments/20130117/da1d0c8c/attachment.html>