[Pw_forum] problems with converge of geometric optimization

[Stephan Rix]

I am trying to calculate an H-center in CaF2, and I am having trouble with
the geometry optimization.
I have tried adjusting various parameters such as ion dynamics, trust
radius, convergence tresholds, but it seems that convergence cannot be
improved.

Using bfgs I always get the following error:

%%%%%%%%%%%%%%%%%%%%%%%%%%
     from bfgs : error #         1
     bfgs history already reset at previous step
 %%%%%%%%%%%%%%%%%%%%%%%%%%

Alternatively the electonic convergence gets extremely slow.

In addition, no matter what parameters I adjust the total forces in the
system never converge, e.g.
     Total force =     0.026394     Total SCF correction =     0.000314
     Total force =     0.018379     Total SCF correction =     0.000282
     Total force =     0.018824     Total SCF correction =     0.000120
     Total force =     0.018857     Total SCF correction =     0.000155
     Total force =     0.020215     Total SCF correction =     0.000193
     Total force =     0.058765     Total SCF correction =     0.000241
     Total force =     0.016998     Total SCF correction =     0.000205
     Total force =     0.042967     Total SCF correction =     0.000238
     Total force =     0.106226     Total SCF correction =     0.000073
     Total force =     0.137142     Total SCF correction =     0.000071
     Total force =     0.109549     Total SCF correction =     0.000108
     Total force =     0.068723     Total SCF correction =     0.000103
     Total force =     0.076599     Total SCF correction =     0.000168
     Total force =     0.033233     Total SCF correction =     0.000342
     Total force =     0.026883     Total SCF correction =     0.000248
     Total force =     0.025846     Total SCF correction =     0.000378
     Total force =     0.025596     Total SCF correction =     0.000225
     Total force =     0.025482     Total SCF correction =     0.000275
     Total force =     0.025508     Total SCF correction =     0.000128

I am thankful for any suggestions.

Stephan Rix
Institute for Inorganic und Analytical Chemistry
Johannes Gutenberg-University Mainz, Germany
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