[QE-users] ph.x electric fields not converging

[Johnson, Miles R.]

Hello all,

I'm trying to converge a phonon calculation for a noncolinear system without spin-orbit coupling, but the electric fields step doesn't seem to converge even after trying a number of things. Here is my input:

&inputph
  verbosity='high'
  tr2_ph=1.0d-14
  prefix='nips3_nonco_U0_444'
  ldisp=.true.
  epsil=.false.
  recover=.true.
  lqdir = .true.
  outdir='./tmp'
  electron_phonon = 'dvscf'
  fildyn  = 'NiPS3.dyn.xml'
  fildvscf = 'dvscf'
  nq1=4, nq2=4, nq3=4,
  start_q=1
  last_q=1
  nmix_ph=12
  alpha_mix=0.2
/

I've tried relaxing the unit cell with tighter parameters in my pw.x calculations and decreasing conv_thr there as well, and I've tried this on a few versions of espresso, from 7.0 to 7.3. For all of them, the electric fields part just iterates 150 times then stops, never going below |ddv_scf|^2 ~  1E-09.

Here's one try with QE 7.3.1

...
 iter # 148 total cpu time : 39144.4 secs   av.it.:  29.0
      thresh= 1.216E-03 alpha_mix =  0.200 |ddv_scf|^2 =  1.370E-04

      iter # 149 total cpu time : 39413.5 secs   av.it.:  31.6
      thresh= 1.170E-03 alpha_mix =  0.200 |ddv_scf|^2 =  3.182E-05

      iter # 150 total cpu time : 39706.5 secs   av.it.:  35.4
      thresh= 5.641E-04 alpha_mix =  0.200 |ddv_scf|^2 =  1.910E-04

     End of electric fields calculation

And here's another with QE 7.2

...
      iter # 148 total cpu time :155111.4 secs   av.it.:  25.6
      thresh= 1.246E-05 alpha_mix =  0.200 |ddv_scf|^2 =  1.546E-08

      iter # 149 total cpu time :156266.3 secs   av.it.:  30.2
      thresh= 1.243E-05 alpha_mix =  0.200 |ddv_scf|^2 =  1.564E-08

      iter # 150 total cpu time :157169.7 secs   av.it.:  23.1
      thresh= 1.251E-05 alpha_mix =  0.200 |ddv_scf|^2 =  1.570E-08

     End of electric fields calculation


If anyone has tips I would love to hear them - I haven't done many phonon calculations before.


Best,
Miles


Miles Johnson
PhD Candidate in Applied Physics
California Institute of Technology
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