[QE-users] scf convergence

[Ramon Sampaio Ferreira]

Hello everyone,

I hope everyone is doing well.

I am confused about the convergence of the system I'm testing. The problem
is the following: at the beginning of the simulation, apparently everything
was going well, but some warning messages appeared and I was a little
afraid if everything is ok with the convergence process.

The first warning message is as follows (a lot of them):

iteration #126     ecut=   100.00 Ry     beta= 0.10
     Davidson diagonalization with overlap
     c_bands:  4 eigenvalues not converged
     c_bands:  1 eigenvalues not converged
     c_bands:  3 eigenvalues not converged

and the other one:

     WARNING: integrated charge=   228.00003355, expected=   228.00000000

My questions are:

->Should I just ignore these messages and continue with the convergence
process?

->What could I modify in the input file to improve the convergence process?

->I am simulating a primitive cell, if I want to simulate a supercell (say
2x2x2), doing the SCF calculation and after that the phonon calculation,
what convergence parameters should I modify in the initial input file?
Reduce ecutwfc, conv_thr, mixing_beta and k-points, for example?

I greatly appreciate any help you can provide. Thank you so much!

The input file is below:

&CONTROL
  calculation = 'scf'
  restart_mode = 'from_scratch'
  outdir = './
  prefix = 'Ce2WO43'
  pseudo_dir = './'
 /
&SYSTEM
  degauss =   1.0000000000d-03
  ecutwfc =   10.0000000000d+01
  ibrav = 0
  nat = 34
  ntyp = 3
  occupations = 'smearing'
  smearing = 'methfessel-paxton'
/
&ELECTRONS
   conv_thr =   1.000000000d-09
   electron_maxstep = 1000
   mixing_beta =   1.0000000000d-01
/
ATOMIC_SPECIES
Ce     140.116 Ce.pz-sp-hgh.UPF
O      15.9994 O.pz-hgh.UPF
W      183.840 W.pz-hgh.UPF
ATOMIC_POSITIONS crystal
Ce           0.7121000000       0.0425510000       0.4051270000
Ce           0.0425510000       0.7121000000       0.0948730000
Ce           0.2879000000       0.9574490000       0.5948730000
Ce           0.9574490000       0.2879000000       0.9051270000
W            0.8656420000       0.8656420000       0.7500000000
W            0.1343580000       0.1343580000       0.2500000000
W            0.5403790000       0.2527450000       0.0464770000
W            0.2527450000       0.5403790000       0.4535230000
W            0.4596210000       0.7472550000       0.9535230000
W            0.7472550000       0.4596210000       0.5464770000
O            0.4718750000       0.6036290000       0.5709640000
O            0.6036290000       0.4718750000       0.9290360000
O            0.5281250000       0.3963710000       0.4290360000
O            0.3963710000       0.5281250000       0.0709640000
O            0.3402810000       0.2311750000       0.9403610000
O            0.2311750000       0.3402810000       0.5596390000
O            0.6597190000       0.7688250000       0.0596390000
O            0.7688250000       0.6597190000       0.4403610000
O            0.8892320000       0.4545640000       0.6956050000
O            0.4545640000       0.8892320000       0.8043950000
O            0.3377230000       0.0819210000       0.3906090000
O            0.0819210000       0.3377230000       0.1093910000
O            0.6622770000       0.9180790000       0.6093910000
O            0.9180790000       0.6622770000       0.8906090000
O            0.8837830000       0.2069030000       0.2811260000
O            0.2069030000       0.8837830000       0.2188740000
O            0.1162170000       0.7930970000       0.7188740000
O            0.7930970000       0.1162170000       0.7811260000
O            0.0843560000       0.8114650000       0.4603700000
O            0.8114650000       0.0843560000       0.0396300000
O            0.9156440000       0.1885350000       0.5396300000
O            0.1885350000       0.9156440000       0.9603700000
O            0.5454360000       0.1107680000       0.1956050000
O            0.1107680000       0.5454360000       0.3043950000
K_POINTS automatic
10 10 10 0 0 0
CELL_PARAMETERS angstrom
      7.1400620600       0.0000000000       0.0000000000
      2.6686708410       6.6225887811       0.0000000000
     -2.2226301817       3.2919431525      11.0483089965
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