[Pw_forum] set_irr error during phonon calculation

[Kun Yin]

Dear Users,

I did two similar phonon runs after a same scf calculation. The only
difference between the two phonon calculations is the dimension of
q-point mesh.

    nq1=2,nq2=2,nq3=2 (in 1st ph.x run)
    nq1=2,nq2=2,nq3=1 (in 2nd ph.x run)

The first calculation was successful to finish, while the second one
met the following error and stopped.

    from set_irr: error# 2
    npert > 6

This problem seems different from someone have asked before which
could be solved by increasing max_irr_dim value in phcom.f90 file.
Actually I didn't find max_irr_dim in this file in QE version 4.2
which I used.

Any suggestions or help will be appreciated.

Kun Yin
Nanjing University,China

Input of scf run:

 &CONTROL
   calculation          =  'scf',
   outdir               =  '/state/partition1/kyin',
   prefix               =  'qe',
   pseudo_dir           =  '/share/apps/qe_pseudo',
   restart_mode         =  'from_scratch',
   title                =  'qe',
   verbosity            =  'high',
 /

 &SYSTEM
   celldm(1)            =  1,
   ecutrho              =  400,
   ecutwfc              =  40,
   ibrav                =  0,
   nat                  =  20,
   ntyp                 =  3,
   nr1=60,nr2=60,nr3=90
 /

 &ELECTRONS
   conv_thr             =  1.0d-9,
   mixing_mode          =  'plain',
 /

ATOMIC_SPECIES
  Mg   24.305   Mg.pw91-np-van.UPF
  Si   28.0855   Si.pw91-n-van.UPF
  O   15.9994   O.pw91-van_ak.UPF

K_POINTS automatic
  4   4   2   0   0   0

CELL_PARAMETERS (alat=  1.00000000)
   7.646348501   0.000000000   0.000000000
   0.000000000   8.393090445   0.000000000
   0.000000000   0.000000000  11.365238746

ATOMIC_POSITIONS (crystal)
Mg       0.533728470   0.589922896   0.250000000
Mg       0.466271530   0.410077104   0.750000000
Mg       0.033728470   0.910077104   0.750000000
Mg       0.966271530   0.089922896   0.250000000
Si       0.500000000   0.000000000   0.500000000

Si       0.500000000   0.000000000   0.000000000
Si       0.000000000   0.500000000   0.500000000
Si       0.000000000   0.500000000   0.000000000
O        0.125931013   0.465888786   0.250000000
O        0.874068987   0.534111214   0.750000000
O        0.625931013   0.034111214   0.750000000
O        0.374068987   0.965888786   0.250000000
O        0.171733094   0.187375245   0.559982148
O        0.828266906   0.812624755   0.440017852
O        0.828266906   0.812624755   0.059982148
O        0.171733094   0.187375245   0.940017852
O        0.671733094   0.312624755   0.440017852
O        0.328266906   0.687375245   0.559982148
O        0.328266906   0.687375245   0.940017852
O        0.671733094   0.312624755   0.059982148

Input of phonon run:
Phonons
 &inputph
  amass(1)=24.3050,
  amass(2)=28.0855,
  amass(3)=15.9994,
  prefix='qe',
  outdir='/state/partition1/kyin'
  fildyn='qe.dyn',
  tr2_ph=1.0d-14,
  ldisp=.true.
  nq1=2,nq2=2,nq3=2
 /