[QE-users] ph.x diverges when restart

[Yujia Teng]

Dear QE community,
I'm using QE v7.3.1. I found that when restarting from phonon calculation, it often diverges. I'm wondering is there a way to avoid this?

For example, 'thresh' was on the order of 1E-09 at the end of previous job. When restart, it jumps from 1E-09 to 1E-03 or 02. and |ddv_scf|^2 changed from 2E-04 to 2E+01. Due to the walltime limit on HPC cluster, I've set 'max_seconds' tag to ensure ph.x ends cleanly. In my initial run, I already lowered alpha_mix to 0.1 and increased nmix_ph to 10 to speed up convergence.
---------------------------ph.out-------------------------------------------
iter #  19 total cpu time :   417.8 secs   av.it.:  22.5
      thresh= 1.794E-09 alpha_mix =  0.100 |ddv_scf|^2 =  2.307E-04

      iter #  20 total cpu time :   440.0 secs   av.it.:   1.0
      thresh= 1.519E-03 alpha_mix =  0.100 |ddv_scf|^2 =  2.301E-04
.
.
.
 iter #  51 total cpu time :  3263.7 secs   av.it.:  20.8
      thresh= 1.000E-02 alpha_mix =  0.100 |ddv_scf|^2 =  1.605E+01

      iter #  52 total cpu time :  3403.6 secs   av.it.:  21.0
      thresh= 1.000E-02 alpha_mix =  0.100 |ddv_scf|^2 =  2.770E+01
------------------------------------------------------------------------
---------------------------ph.in-------------------------------------------
phonons of GdAuGe at q=3
 &inputph
  tr2_ph=1.0d-16,
  prefix='GdAuGe',
  outdir='./tmp/3',
  fildyn='GdAuGe.dyn',
  fildvscf='dvscf',
  ldisp=.true.,
  nq1=6, nq2=6, nq3=3,
  start_q=3,
  last_q=3,
  recover=.true.,
  alpha_mix(1) = 0.1,
  nmix_ph=10,
  max_seconds=13500,
 /
------------------------------------------------------------------------

Best,
Yujia
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