[QE-users] Non-convergence in PWscf without smearing and phonon calculation

[ykhuang at dicp.ac.cn]

Greeting, QE users and experts.

I want to calculate vibrational modes of metal atom that absorbed on rutile (TiO2), however, I find pw.x module can't converge at all if I turn off "smearing". I have tried changed mixing_mode from plain to local-TF, reduced mixing_beta to 0.1, but all was in vain.

Q1: what's wrong with my system? Does it mean that my system is actually metallic?

What's worse, after I completed scf calculation (added smearing with degauss=0.002) and turned to ph.x, convergence oscillated, then exploded after about 50 iterations:

1-8:

      thresh= 1.000E-02 alpha_mix =  0.700 |ddv_scf|^2 =  7.296E-07
      thresh= 1.000E-02 alpha_mix =  0.700 |ddv_scf|^2 =  6.558E-05
      thresh= 1.000E-02 alpha_mix =  0.700 |ddv_scf|^2 =  1.732E-04
      thresh= 1.000E-02 alpha_mix =  0.700 |ddv_scf|^2 =  1.231E-02
      thresh= 1.000E-02 alpha_mix =  0.700 |ddv_scf|^2 =  5.254E-03
      thresh= 1.000E-02 alpha_mix =  0.700 |ddv_scf|^2 =  5.072E-02
      thresh= 1.000E-02 alpha_mix =  0.700 |ddv_scf|^2 =  1.621E-01
      thresh= 1.000E-02 alpha_mix =  0.700 |ddv_scf|^2 =  4.011E+00




51-58:

      thresh= 1.000E-02 alpha_mix =  0.700 |ddv_scf|^2 =  2.663E+04
      thresh= 1.000E-02 alpha_mix =  0.700 |ddv_scf|^2 =  1.416E+07
      thresh= 1.000E-02 alpha_mix =  0.700 |ddv_scf|^2 =  6.096E+06
      thresh= 1.000E-02 alpha_mix =  0.700 |ddv_scf|^2 =  1.458E+06
      thresh= 1.000E-02 alpha_mix =  0.700 |ddv_scf|^2 =  2.034E+06
      thresh= 1.000E-02 alpha_mix =  0.700 |ddv_scf|^2 =  1.185E+07
      thresh= 1.000E-02 alpha_mix =  0.700 |ddv_scf|^2 =  6.708E+06
      thresh= 1.000E-02 alpha_mix =  0.700 |ddv_scf|^2 =  2.834E+06


99-100:

      thresh= 1.000E-02 alpha_mix =  0.700 |ddv_scf|^2 =  2.264E+11
      thresh= 1.000E-02 alpha_mix =  0.700 |ddv_scf|^2 =  3.491E+10


Q2: note that in ph.x, I can't find ways as smearing in pw.x module, what can I do to improve convergence? I have searched posts in archive, it seems that explosion of convergence means "something" but I don't know what exactly that is, could anybody tell me?




Thanks in advance.




Huang Yike, PhD candidate.

Dalian Institute of Chemical Physics, CAS, China.
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.quantum-espresso.org/pipermail/users/attachments/20200512/80c68ecd/attachment.html>