[QE-users] [SPAM] Convergence problems

[Pietro Davide Delugas]

Hello
a few suggestions:


  1.  The convergence issues you are experiencing may be due to your starting configuration; check that it is a sensible one.
  2.
Use a larger smearing, and if you are using an old version of qe, try to switch to gauss smearing,
  3.
 Diagonalization='cg' is very slow and inefficient; unless Davidson fails, it is better to  stick to that; otherwise

              diagonalization='rmm-davidson' or 'rmm-paro'.

        5) If you are not using a recent version of qe ( 7.2 or older ), avoid using local-TF because, in some cases, it could lead to practically infinite loops. This behaviour has been fixed in qe-7.3.
       6) Interpolating potential and wave functions is not helpful for relaxations because steps are generally longer than in dynamics.

         7) conv_thr=10^-6 is a too high threshold to obtain any reliable relaxation, it may be good for the very first steps of the relaxation but as soon as the forces become small you will need to use a lower threshold at least  > 10^-8 to make the relaxation converge.

best regards
Pietro

________________________________
From: users <users-bounces at lists.quantum-espresso.org> on behalf of Janiny <djaniny at uol.com.br>
Sent: Wednesday, July 3, 2024 18:26
To: users at lists.quantum-espresso.org <users at lists.quantum-espresso.org>
Subject: [QE-users] [SPAM] Convergence problems


Dear all,

1) I am conducting an adsorption study, and convergence is taking too long (in some cases, over 20 days). Additionally, there are situations where more than 100 iterations pass without generating coordinates. Is it possible to periodically fix the coordinate generation?

2) I am using conv_thr = 10^-6. Do you suggest any other parameters that I could adjust to improve convergence?

 &control
  calculation='relax'
    wf_collect = .TRUE.
!  restart_mode = 'restart'
  max_seconds = 1.D+10
  disk_io='low'
/
 &system
    ibrav = 0, celldm(1) =xxx,nat=xxx, ntyp= xxx,
    ecutwfc = 55.0, ecutrho = 600,
    occupations='smearing', smearing='marzari-vanderbilt', degauss=0.01
    nspin= xxx
    tot_magnetization= xxx
 /
 &electrons
    conv_thr = 1.0e-6
    mixing_beta = 0.1
    mixing_mode= 'local-TF'
    electron_maxstep=500
    diago_thr_init = 1e-4
    diagonalization = 'cg'
/
&ions
ion_dynamics = 'bfgs'
pot_extrapolation = 'second_order'
wfc_extrapolation = 'second_order'


Best regards,
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