[QE-users] Phonon calculation with QE-7.3.1 diverges upon restart

[Vahid Askarpour]

Dear QE Community,

Phonon calculations with QE-7.3.1 and the following inputs for scf.in and ph.in ran fine until the phonon job stopped due to time limit allowed by the system.
Upon restart, the calculations began diverging as shown below:

&CONTROL
  calculation = 'scf'
  etot_conv_thr =   1.0d-6
  forc_conv_thr =   1.0d-5
  outdir = './'
  prefix = 'I2K'
  pseudo_dir = './' 
  tprnfor = .true.
  tstress = .true.
  verbosity = 'high'
/
&SYSTEM
  ecutwfc=   160
  ecutrho =  700
  ibrav = 0
  nat = 6
  ntyp = 2
  occupations = 'smearing'
  smearing = 'gauss'
  degauss=0.02
  lspinorb=.true.
  noncolin=.true.
  vdw_corr = 'dft-d3',
  dftd3_version=4,
  dftd3_threebody=.false.
/
&ELECTRONS
  conv_thr =   1.0d-10
  electron_maxstep = 500
  mixing_mode='local-TF'
  !mixing_beta=   0.3
/
ATOMIC_SPECIES
K    39.098    K.rel-pbe-spn-kjpaw_psl.1.0.0.UPF
I   126.90447 I.rel-pbe-n-kjpaw_psl.1.0.0.UPF

CELL_PARAMETERS (angstrom)
   4.583731831   0.000000000   0.000000000
   0.000000000   9.157438007   0.000000000
   0.000000000   0.000000000  30.000000000

ATOMIC_POSITIONS (crystal)
K                0.9997969746        0.7500016722        0.0831641299
I                0.5000769219        0.5000083873        0.0279334092
I                0.5001053393       -0.0000100595        0.1384074610
K                0.0002030254        0.2500016722        0.0831641299
I                0.4999230781        1.0000083873        0.0279334092
I                0.4998946607        0.4999899405        0.1384074610

K_POINTS (automatic)
10 6  1 0 0 0


I2K
&inputph
  tr2_ph   =  1.0d-20
  prefix   = 'I2K'
  recover  = .true.
  amass(1) =  39.098
  amass(2) =  126.90447
  ldisp=.true.
  nq1=8, nq2=4, nq3=1
  dftd3_hess='hess.dat'
  start_q=14
  last_q=14
  outdir   = './'
  alpha_mix(1) = 0.3
  fildyn   = 'I2K.dyn'
  fildvscf = 'dvscf'
 /

The output is:

    Representation     1      1 modes -  Done

     Representation     2      1 modes -  Done

     Representation     3      1 modes -  Done

     Representation     4      1 modes -  Done

     Representation     5      1 modes -  Done

     Representation     6      1 modes -  Done

     Representation     7      1 modes -  Done

     Representation     8      1 modes -  Done

     Representation     9      1 modes -  Done

     Representation    10      1 modes -  Done

     Representation    11      1 modes -  Done

     Representation    12      1 modes -  Done

     Representation    13      1 modes -  Done

     Representation    14      1 modes -  Done

     Representation    15      1 modes -  Done

     Representation    16      1 modes -  Done

     Representation    17      1 modes -  Done

     Representation    18      1 modes -  To be done


     Message from routine init_vloc:
     Interpolation table for Vloc re-allocated
     PHONON       :   8m54.89s CPU  10m 7.09s WALL



     Representation #  18 mode #  18

     Self-consistent Calculation

      iter #  21 total cpu time :  1036.6 secs   av.it.:   8.9
      thresh= 8.885E-11 alpha_mix =  0.300 |ddv_scf|^2 =  3.607E+04

      iter #  22 total cpu time :  1326.3 secs   av.it.:  13.1
      thresh= 1.000E-02 alpha_mix =  0.300 |ddv_scf|^2 =  3.315E+11

      iter #  23 total cpu time :  1725.9 secs   av.it.:  22.3
      thresh= 1.000E-02 alpha_mix =  0.300 |ddv_scf|^2 =  6.946E+17

      iter #  24 total cpu time :  2309.8 secs   av.it.:  32.8
      thresh= 1.000E-02 alpha_mix =  0.300 |ddv_scf|^2 =  4.610E+24


Is this a bug or an error on my part? 

Thanks,
Vahid

Vahid Askarpour
Department of Physics and Atmospheric Science
Dalhousie University
Halifax, NS, CANADA