[Pw_forum] problem with phonon calculation

[chaitanya varma]

Dear sir,when i ran the phonon calculation for PbTiO3 with tetragonal structure in the output file i got negative frequencies and negative dielectric constant, can i know where i did worng.Convergence has been achieved 

     Number of q in the star =    1
     List of q in the star:
          1   0.000000000   0.000000000   0.000000000

          Dielectric constant in cartesian axis 

          (      53.479682169      -4.588399890     -12.973363015 )
          (      -4.588399085      40.178849877       4.029708708 )
          (     -12.973363359       4.029706013      59.207850004 )
Diagonalizing the dynamical matrix

     q = (    0.000000000   0.000000000   0.000000000 ) 

 **************************************************************************
     freq (    1) =     -26.415709 [THz] =    -881.133205 [cm-1]
     freq (    2) =     -20.796909 [THz] =    -693.710200 [cm-1]
     freq (    3) =     -17.827704 [THz] =    -594.668189 [cm-1]
     freq (    4) =      -7.991439 [THz] =    -266.565722 [cm-1]
     freq (    5) =       0.272538 [THz] =       9.090898 [cm-1]
     freq (    6) =       0.904088 [THz] =      30.157139 [cm-1]
     freq (    7) =       1.108034 [THz] =      36.960023 [cm-1]
     freq (    8) =      18.450705 [THz] =     615.449285 [cm-1]
     freq (    9) =      26.323046 [THz] =     878.042300 [cm-1]
     freq (   10) =      44.247850 [THz] =    1475.949412 [cm-1]
     freq (   11) =      57.065006 [THz] =    1903.483720 [cm-1]
     freq (   12) =      58.078593 [THz] =    1937.293337 [cm-1]
 **************************************************************************

     Mode symmetry, C_1 (1)     point group:

     freq (  1 -  1) =       -881.1  [cm-1]   --> A               I+R
     freq (  2 -  2) =       -693.7  [cm-1]   --> A               I+R
     freq (  3 -  3) =       -594.7  [cm-1]   --> A               I+R
     freq (  4 -  4) =       -266.6  [cm-1]   --> A               I+R
     freq (  5 -  5) =          9.1  [cm-1]   --> A               I+R
     freq (  6 -  6) =         30.2  [cm-1]   --> A               I+R
     freq (  7 -  7) =         37.0  [cm-1]   --> A               I+R
     freq (  8 -  8) =        615.4  [cm-1]   --> A               I+R
     freq (  9 -  9) =        878.0  [cm-1]   --> A               I+R
     freq ( 10 - 10) =       1475.9  [cm-1]   --> A               I+R
     freq ( 11 - 11) =       1903.5  [cm-1]   --> A               I+R
     freq ( 12 - 12) =       1937.3  [cm-1]   --> A               I+R regards
Chaitanya Varma M  Assistant professorDept of PhysicsGITAM UniversityVisakhapatnam, India
 


     On Saturday, 5 September 2015 2:18 PM, dario rocca <roccad at gmail.com> wrote:
   

 Dear Chaitanya
As the error message says you cannot use "occupations=tetrahedra" with the phonon code since this approach is not implemented 
The only solution is to use a smearing instead
Best regards,
Dario

On Sat, Sep 5, 2015 at 8:39 AM, chaitanya varma <chvar81 at yahoo.co.in> wrote:

Dear Sir,I am trying to calculate DOS, pDOS and phonon densities etc of PbTiO3 -(tetragonal structure)SCF, NSCF and BANDS calculations worked out nicely with tetrahedra,but while doing ph.x calculation i am getting the following error

 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
     Error in routine phq_setup (1):
     phonon + tetrahedra not implemented
 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

     stopping ...
can i know where i am doing wrong.i am attaching the scf.in and phG.in/out files
thanks and regards Chaitanya Varma MAsst ProfessorGITAM UniversityIndia
  
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