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._______________________________________________
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