[QE-users] Directory mismatch and too few bands problem in split irr calculation in ph.x

[Yujia Teng]

There’s another problem I forgot to mention, which is empty ‘dvscf’ file. But ‘dvscf’ file is not empty if I split q only or don’t split the calculation.

I found this previous post [Q-e-developers] bug image parallelization in PHonon<https://lists.quantum-espresso.org/pipermail/developers/2016-September/001388.html> reporting same issue when using image parallelization, but it says works in GRID way (split q). So I’m wondering is splitting irr calculation similar to the image parallelization, which just doesn’t work for non-empty ‘dvscf’ file?

Looks like I can’t attach file here. I would just copy past part of input/output files I attached in my initial email below.

----------------<input.2.16>---------------------
phonons of GdAuGe q=2 irr=16
&inputph
  tr2_ph=1.0d-18,
  prefix='GdAuGe',
  outdir='./tmp/2.16',
  fildyn='GdAuGe.dyn',
  ldisp=.true.,
  nq1=3, nq2=3, nq3=1,
  start_q=2,
  last_q=2,
  start_irr=16,
  last_irr=16,
  lqdir=.true.,
  !recover=.true.,
  alpha_mix(1)=0.1,   ! Added: Much more conservative mixing for stability
  nmix_ph=10,         ! Added: More iterations for the mixing algorithm
/
----------------------------------------------
----------------<output.2.16>---------------
……
Waiting for input...
     Reading input from standard input

     Reading xml data from directory:

     ./tmp/3.14/GdAuGe.save/
……
---------------------------------------------
----------------<ph-collect.in>---------------------
phonons of GdAuGe at Gamma
&inputph
  tr2_ph=1.0d-12,
  prefix='GdAuGe',
  outdir='./tmp',
  fildyn='GdAuGe.dyn',
  fildvscf='dvscf',
  ldisp=.true.,
  nq1=3, nq2=3, nq3=1,
  recover=.true.
/
--------------------------------------------
----------------<ph-collect.out>---------------------
     The potential is recalculated from file :
     ./tmp/_ph0/GdAuGe.q_2/GdAuGe.save/charge-density

     Starting wfcs are  124 atomic +  132 random wfcs
     Checking if some PAW data can be deallocated...

Possibly too few bands at point    1   0.00000   0.00000   0.00000

Possibly too few bands at point    2   0.00000   0.38490   0.00000
--------------------------------------------

发件人: Yujia Teng
发送时间: 2026年1月7日 10:33
收件人: users at lists.quantum-espresso.org
主题: Directory mismatch and too few bands problem in split irr calculation in ph.x

Dear QE forum,
I had the following 2 problems related to split irrep in ph.x calculation and wondering how to solve them. I’m following the GRID_example.


  1.  There’s always directory mismatch problem of some q and irr, when I split irrep. For example, for q=2,irr=1, the tmp dir is ‘./tmp/1.2’, but in its output file, it reads other tmp directory, like ‘./tmp/3.7’. I already set low_directory_check=.true., but this doesn’t work. Sometimes, it even reports namelist error in the input file but there’s no. My current solution is to write a check script to find these failed jobs and resubmit them.



  1.  There’s always ‘Too few bands at k point xxx’ warning when I collect the result, even if I increased nbnd a lot. My system has 124 wfcs, I increased nbnd up to 256 but the warning is still present. But there’s no such warning if I split q-point only or don’t split. I did a convergence test w.r.t nbnd on a small q-point grid, and in my system the phonon dispersion converges (or same as no split result) at nbnd=192, although the warning is still there. I’m not sure if the result is still correct for denser parameters.


Is there a way to fully avoid the problems above? I attach some input/outputs in zip file here.

Best,
Yujia
Rutgers University.


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