[Pw_forum] Issue with phonon calculation on supercell.

[Éric Germaneau]

Dear all,

I'm attempting to compute phonon at gamma point of a 2x2x2 crystal 
structure but I get the error bellow :

    *.....*
          Atomic displacements:
          There are 192 irreducible representations

          Representation     1      1 modes - To be done

          Representation     2      1 modes - To be done
    *....*
          Representation   191      1 modes - To be done

          Representation   192      1 modes - To be done


          Alpha used in Ewald sum =   2.8000
          PHONON       : 51m 2.98s CPU    51m13.49s WALL


          Electric Fields Calculation

      %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
          from calbec : error #         1
          size mismatch
      %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

          stopping ...
    Signal 15 received.
    Signal 15 received.
    Signal 15 received.
    Signal 15 received.
    Signal 15 received.
    Signal 15 received.
    Signal 15 received.
    Signal 15 received.
    Signal 15 received.
    Signal 15 received.
    Signal 15 received.
    Signal 15 received.
    Signal 15 received.

Here is my input

    phonons
    &inputph
       tr2_ph=1.0d-14,
       prefix='S007__086_B4N4.vcrelax.vcrelax_2x2x2',
       epsil=.true.,
       amass(1)=10.811000,
       amass(2)=14.006700,
         outdir='./SCF_PH',
         fildyn='S007__086_B4N4.vcrelax.vcrelax_2x2x2.dynG',
        /
       0.0 0.0 0.0

What sounds weird to me is that I don't have any problem when I perform 
the same calculation on the unit cell, I mean the 1x1x1 structure.
Before running ph.x I do a regular scf calculation at gamma point only 
which ends normally:

    K_POINTS automatic
    1 1 1   0 0 0

I generate my supercell from the optimized unit cell and do not 
optimized it again due to time consuming.
I don't have much experience in phonon calculations so any hits are welcome.
Thank you,

                   Éric.

-- 
/Be the change you wish to see in the world
/ --- Mahatma Gandhi ---

Dr. Éric Germaneau 
<http://www.linkedin.com/pub/%C3%A9ric-germaneau/30/931/986>

Graduate University of Chinese Academy of Sciences
College of Physical Sciences
Yuquan Road 19A
Beijing 100049
China

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