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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. 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 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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