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geometry relaxation
Date: 2007/07/04 22:08
Name: JessK


Dr. Ozaki,

I am trying to relax a surface. I put a force criteria 4.0d-4 Ha/bohr, and use DIIS method for that. There is no SCF convergence problem, but relaxation is very very slow - it passed about 300 steps, but forces oscillate around one value. Are there any parameters which could help?


<Steepest_Descent> |Maximum force| (Hartree/Bohr) = 0.004734148175
<Steepest_Descent> |Maximum force| (Hartree/Bohr) = 0.004922389624
<DIIS> |Maximum force| (Hartree/Bohr) = 0.005641408054
<DIIS> |Maximum force| (Hartree/Bohr) = 0.006429973134
<DIIS> |Maximum force| (Hartree/Bohr) = 0.008364579772
<DIIS> |Maximum force| (Hartree/Bohr) = 0.003883459762
<DIIS> |Maximum force| (Hartree/Bohr) = 0.003494295620
<DIIS> |Maximum force| (Hartree/Bohr) = 0.003565106358
<DIIS> |Maximum force| (Hartree/Bohr) = 0.003808776831
<DIIS> |Maximum force| (Hartree/Bohr) = 0.003518174225
<DIIS> |Maximum force| (Hartree/Bohr) = 0.003190680359
<DIIS> |Maximum force| (Hartree/Bohr) = 0.003280411383
<Steepest_Descent> |Maximum force| (Hartree/Bohr) = 0.006639887540
<Steepest_Descent> |Maximum force| (Hartree/Bohr) = 0.005232858642
<Steepest_Descent> |Maximum force| (Hartree/Bohr) = 0.004440083714
<Steepest_Descent> |Maximum force| (Hartree/Bohr) = 0.004114006691
<Steepest_Descent> |Maximum force| (Hartree/Bohr) = 0.004327090157
<Steepest_Descent> |Maximum force| (Hartree/Bohr) = 0.005095942923
<Steepest_Descent> |Maximum force| (Hartree/Bohr) = 0.006376893247
<Steepest_Descent> |Maximum force| (Hartree/Bohr) = 0.008481134569
<Steepest_Descent> |Maximum force| (Hartree/Bohr) = 0.011454567615
<Steepest_Descent> |Maximum force| (Hartree/Bohr) = 0.015366560529
<DIIS> |Maximum force| (Hartree/Bohr) = 0.016115039728
<DIIS> |Maximum force| (Hartree/Bohr) = 0.016434052761
<DIIS> |Maximum force| (Hartree/Bohr) = 0.014963018847
<DIIS> |Maximum force| (Hartree/Bohr) = 0.010052082220
<DIIS> |Maximum force| (Hartree/Bohr) = 0.007140709704
<DIIS> |Maximum force| (Hartree/Bohr) = 0.006686724870
<DIIS> |Maximum force| (Hartree/Bohr) = 0.005499107286
<DIIS> |Maximum force| (Hartree/Bohr) = 0.005175443078
<DIIS> |Maximum force| (Hartree/Bohr) = 0.004016993191
<DIIS> |Maximum force| (Hartree/Bohr) = 0.002961278589
<Steepest_Descent> |Maximum force| (Hartree/Bohr) = 0.004001748498
<Steepest_Descent> |Maximum force| (Hartree/Bohr) = 0.003882077410
<Steepest_Descent> |Maximum force| (Hartree/Bohr) = 0.003893408575
<Steepest_Descent> |Maximum force| (Hartree/Bohr) = 0.004033210610
<Steepest_Descent> |Maximum force| (Hartree/Bohr) = 0.004114949478
<Steepest_Descent> |Maximum force| (Hartree/Bohr) = 0.004298120234
<Steepest_Descent> |Maximum force| (Hartree/Bohr) = 0.004485083905
<Steepest_Descent> |Maximum force| (Hartree/Bohr) = 0.004570423744
<Steepest_Descent> |Maximum force| (Hartree/Bohr) = 0.004824545345
<Steepest_Descent> |Maximum force| (Hartree/Bohr) = 0.004987265999
<DIIS> |Maximum force| (Hartree/Bohr) = 0.003842487255
<DIIS> |Maximum force| (Hartree/Bohr) = 0.004056208063
<DIIS> |Maximum force| (Hartree/Bohr) = 0.003679225273
<DIIS> |Maximum force| (Hartree/Bohr) = 0.002953778425
<DIIS> |Maximum force| (Hartree/Bohr) = 0.003514826512
<DIIS> |Maximum force| (Hartree/Bohr) = 0.003140333926
<DIIS> |Maximum force| (Hartree/Bohr) = 0.003137441515
<DIIS> |Maximum force| (Hartree/Bohr) = 0.003154661583
<DIIS> |Maximum force| (Hartree/Bohr) = 0.003237588895
<DIIS> |Maximum force| (Hartree/Bohr) = 0.003342009854
<Steepest_Descent> |Maximum force| (Hartree/Bohr) = 0.004031431833
<Steepest_Descent> |Maximum force| (Hartree/Bohr) = 0.004068472953
<Steepest_Descent> |Maximum force| (Hartree/Bohr) = 0.003923797293
<Steepest_Descent> |Maximum force| (Hartree/Bohr) = 0.003958764119
<Steepest_Descent> |Maximum force| (Hartree/Bohr) = 0.004035131394
<Steepest_Descent> |Maximum force| (Hartree/Bohr) = 0.004063828708
<Steepest_Descent> |Maximum force| (Hartree/Bohr) = 0.004056360143
<Steepest_Descent> |Maximum force| (Hartree/Bohr) = 0.004047979732
<Steepest_Descent> |Maximum force| (Hartree/Bohr) = 0.004345450222
<Steepest_Descent> |Maximum force| (Hartree/Bohr) = 0.004775394905
<DIIS> |Maximum force| (Hartree/Bohr) = 0.004753100400
<DIIS> |Maximum force| (Hartree/Bohr) = 0.004095718748
<DIIS> |Maximum force| (Hartree/Bohr) = 0.005284600282
<DIIS> |Maximum force| (Hartree/Bohr) = 0.004442768011
<DIIS> |Maximum force| (Hartree/Bohr) = 0.003670183641
<DIIS> |Maximum force| (Hartree/Bohr) = 0.003570650150
<DIIS> |Maximum force| (Hartree/Bohr) = 0.003445412072
<DIIS> |Maximum force| (Hartree/Bohr) = 0.003522990464
<DIIS> |Maximum force| (Hartree/Bohr) = 0.003538940523
<DIIS> |Maximum force| (Hartree/Bohr) = 0.004506627192
<Steepest_Descent> |Maximum force| (Hartree/Bohr) = 0.004551521577
<Steepest_Descent> |Maximum force| (Hartree/Bohr) = 0.004666136842
<Steepest_Descent> |Maximum force| (Hartree/Bohr) = 0.004783940535
<Steepest_Descent> |Maximum force| (Hartree/Bohr) = 0.004894237769
<Steepest_Descent> |Maximum force| (Hartree/Bohr) = 0.004874370042
<Steepest_Descent> |Maximum force| (Hartree/Bohr) = 0.004849225718
<Steepest_Descent> |Maximum force| (Hartree/Bohr) = 0.004977702338
<Steepest_Descent> |Maximum force| (Hartree/Bohr) = 0.004946515199
<Steepest_Descent> |Maximum force| (Hartree/Bohr) = 0.005077942377
<Steepest_Descent> |Maximum force| (Hartree/Bohr) = 0.005053019091
<DIIS> |Maximum force| (Hartree/Bohr) = 0.004256245025
<DIIS> |Maximum force| (Hartree/Bohr) = 0.004478513265
<DIIS> |Maximum force| (Hartree/Bohr) = 0.005547334818
<DIIS> |Maximum force| (Hartree/Bohr) = 0.003987146430
<DIIS> |Maximum force| (Hartree/Bohr) = 0.003475534544
<DIIS> |Maximum force| (Hartree/Bohr) = 0.003387796841
<DIIS> |Maximum force| (Hartree/Bohr) = 0.003519442917
<DIIS> |Maximum force| (Hartree/Bohr) = 0.003814156830
<DIIS> |Maximum force| (Hartree/Bohr) = 0.003440362284
<DIIS> |Maximum force| (Hartree/Bohr) = 0.003562940194
<Steepest_Descent> |Maximum force| (Hartree/Bohr) = 0.005014759405
<Steepest_Descent> |Maximum force| (Hartree/Bohr) = 0.004986902644
<Steepest_Descent> |Maximum force| (Hartree/Bohr) = 0.004990464445
<Steepest_Descent> |Maximum force| (Hartree/Bohr) = 0.004906274298
<Steepest_Descent> |Maximum force| (Hartree/Bohr) = 0.004944988498
<Steepest_Descent> |Maximum force| (Hartree/Bohr) = 0.004895685639

thanks,
jk
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Re: geometry relaxation ( No.1 )
Date: 2007/07/05 03:59
Name: Vasilii Artyukhov

I think that this problem has already been discussed several times here. This maybe a feature of the algorithm... But! you could try and tell us what happens if you increase the integration grid cutoff, this parameter _can_ cause this kind of a problem, especially with GGA.
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Re: geometry relaxation ( No.2 )
Date: 2007/07/06 02:43
Name: JessK


Hi,

I increased cutoff from 150 Ry to 320 Ry and it looks better now (forces slowly go down). But I wonder, why steepest descent (SD) method is used when DIIS methos is chosen. From manual, it said that first N steps are SD method, and next - DIIS. But from output I see that relaxation method switches from SD to DIIS, and so on.

jk
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Re: geometry relaxation ( No.3 )
Date: 2007/07/06 06:10
Name: Vasilii Artyukhov

Perhaps you should see some literature on DIIS, it might be the normal behavior. It can still be a bug, though... Anyway, the important thing is that the problem is more or less solved - is it?
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