[Pw_forum] problem with vc-relax

Stefano Baroni baroni at sissa.it
Wed Jan 7 13:24:21 CET 2009


On Jan 7, 2009, at 1:19 PM, Stefano de Gironcoli wrote:

> loc duong ding wrote:
>> Dear all,
>>
>> I have a problem when I run vc-relax input file.
>> The force is increasing when the energy is decreasing.
>> I wonder this is the normal case or not.
>>
> this may indicate that you starter from (close to ) a saddle point and
> so you are moving away from a local maximum.
> as long as the energy decreases it should be ok.

another more exotic possibility is that the energy gain due to a  
decreasing stress is larger than the increase due to an increasing  
force. I am not sure that the algorithm implemented guarantees that  
the individual components of the energy gradients decrease during  
along the minimization process.

Stefano B

>
> stefano
>
>>
>>     Total force =     0.008423     Total SCF correction =      
>> 0.001451
>>     Total force =     0.250397     Total SCF correction =      
>> 0.001413
>>     Total force =     0.050557     Total SCF correction =      
>> 0.000845
>>     Total force =     0.023345     Total SCF correction =      
>> 0.000806
>>     Total force =     0.023806     Total SCF correction =      
>> 0.000490
>>     Total force =     0.012668     Total SCF correction =      
>> 0.000976
>>     Total force =     0.018448     Total SCF correction =      
>> 0.000564
>>     Total force =     0.007273     Total SCF correction =      
>> 0.000217
>>     Total force =     0.009299     Total SCF correction =      
>> 0.000773
>>     Total force =     0.020024     Total SCF correction =      
>> 0.000250
>>     Total force =     0.020090     Total SCF correction =      
>> 0.000275
>>     Total force =     0.019091     Total SCF correction =      
>> 0.000327
>>     Total force =     0.015802     Total SCF correction =      
>> 0.000400
>>     Total force =     0.015637     Total SCF correction =      
>> 0.000278
>>     Total force =     0.016418     Total SCF correction =      
>> 0.000350
>>     Total force =     0.015572     Total SCF correction =      
>> 0.000426
>>     Total force =     0.012873     Total SCF correction =      
>> 0.001104
>>     Total force =     0.010242     Total SCF correction =      
>> 0.000505
>>     Total force =     0.011922     Total SCF correction =      
>> 0.000188
>>     Total force =     0.010932     Total SCF correction =      
>> 0.000262
>>     Total force =     0.009932     Total SCF correction =      
>> 0.000551
>>     Total force =     0.011343     Total SCF correction =      
>> 0.000600
>>     Total force =     0.014450     Total SCF correction =      
>> 0.000690
>>     Total force =     0.014524     Total SCF correction =      
>> 0.000966
>>     Total force =     0.011143     Total SCF correction =      
>> 0.000587
>>     Total force =     0.009504     Total SCF correction =      
>> 0.000221
>>     Total force =     0.011470     Total SCF correction =      
>> 0.000335
>>     Total force =     0.014026     Total SCF correction =      
>> 0.000562
>>     Total force =     0.014418     Total SCF correction =      
>> 0.000610
>>     Total force =     0.014141     Total SCF correction =      
>> 0.000876
>>     Total force =     0.014633     Total SCF correction =      
>> 0.000997
>>     Total force =     0.015387     Total SCF correction =      
>> 0.001111
>>     Total force =     0.015936     Total SCF correction =      
>> 0.001014
>>     Total force =     0.015588     Total SCF correction =      
>> 0.000677
>>     Total force =     0.014659     Total SCF correction =      
>> 0.000955
>>     Total force =     0.013135     Total SCF correction =      
>> 0.000591
>>     Total force =     0.011533     Total SCF correction =      
>> 0.000887
>>     Total force =     0.011797     Total SCF correction =      
>> 0.000345
>>     Total force =     0.011249     Total SCF correction =      
>> 0.000261
>>     Total force =     0.009558     Total SCF correction =      
>> 0.000150
>>     Total force =     0.009430     Total SCF correction =      
>> 0.000226
>>     Total force =     0.009257     Total SCF correction =      
>> 0.000241
>>     Total force =     0.010596     Total SCF correction =      
>> 0.000144
>>     Total force =     0.011993     Total SCF correction =      
>> 0.000211
>>     Total force =     0.012208     Total SCF correction =      
>> 0.000626
>>     Total force =     0.011316     Total SCF correction =      
>> 0.000538
>>     Total force =     0.012541     Total SCF correction =      
>> 0.000283
>>     Total force =     0.013752     Total SCF correction =      
>> 0.000313
>>     Total force =     0.014861     Total SCF correction =      
>> 0.000345
>>     Total force =     0.014663     Total SCF correction =      
>> 0.000492
>>
>>
>> !    total energy              =  -311.65667063 Ry
>> !    total energy              =  -311.53467416 Ry
>> !    total energy              =  -311.65476738 Ry
>> !    total energy              =  -311.65809859 Ry
>> !    total energy              =  -311.65746738 Ry
>> !    total energy              =  -311.65818908 Ry
>> !    total energy              =  -311.65836015 Ry
>> !    total energy              =  -311.65850034 Ry
>> !    total energy              =  -311.65862191 Ry
>> !    total energy              =  -311.65888214 Ry
>> !    total energy              =  -311.65922406 Ry
>> !    total energy              =  -311.65963798 Ry
>> !    total energy              =  -311.66003012 Ry
>> !    total energy              =  -311.66040611 Ry
>> !    total energy              =  -311.66078796 Ry
>> !    total energy              =  -311.66117923 Ry
>> !    total energy              =  -311.66141965 Ry
>> !    total energy              =  -311.66161990 Ry
>> !    total energy              =  -311.66177274 Ry
>> !    total energy              =  -311.66190991 Ry
>> !    total energy              =  -311.66205510 Ry
>> !    total energy              =  -311.66222069 Ry
>> !    total energy              =  -311.66243963 Ry
>> !    total energy              =  -311.66268794 Ry
>> !    total energy              =  -311.66289592 Ry
>> !    total energy              =  -311.66304908 Ry
>> !    total energy              =  -311.66320915 Ry
>> !    total energy              =  -311.66340482 Ry
>> !    total energy              =  -311.66361063 Ry
>> !    total energy              =  -311.66386806 Ry
>> !    total energy              =  -311.66413998 Ry
>> !    total energy              =  -311.66442184 Ry
>> !    total energy              =  -311.66467976 Ry
>> !    total energy              =  -311.66497799 Ry
>> !    total energy              =  -311.66518668 Ry
>> !    total energy              =  -311.66545797 Ry
>> !    total energy              =  -311.66563977 Ry
>> !    total energy              =  -311.66584671 Ry
>> !    total energy              =  -311.66601473 Ry
>> !    total energy              =  -311.66615866 Ry
>> !    total energy              =  -311.66626437 Ry
>> !    total energy              =  -311.66638311 Ry
>> !    total energy              =  -311.66651248 Ry
>> !    total energy              =  -311.66665949 Ry
>> !    total energy              =  -311.66687447 Ry
>> !    total energy              =  -311.66704465 Ry
>> !    total energy              =  -311.66725797 Ry
>> !    total energy              =  -311.66744622 Ry
>> !    total energy              =  -311.66766939 Ry
>> !    total energy              =  -311.66791148 Ry
>>
>> Another problem is related c_bands eigenvalue. I often get the  
>> notice:
>>
>> Davidson diagonalization with overlap
>> c_bands:  1 eigenvalues not converged
>> c_bands:  1 eigenvalues not converged
>>
>>
>> But It until runs well. I wonder the result for this calculation is  
>> believable or not.
>>
>> Best regards,
>> -----------------------------------------------
>> Loc Duong Dinh
>> Ms-Ph.D Student
>> Sungkyunkwan Advanced Institute of Nanotechnology,
>> Sungkyunkwan University,
>> Suwon, 440-746, Korea
>> Email: mambom1902 at yahoo.com
>>
>>
>>
>>
>> _______________________________________________
>> Pw_forum mailing list
>> Pw_forum at pwscf.org
>> http://www.democritos.it/mailman/listinfo/pw_forum
>>
>
> _______________________________________________
> Pw_forum mailing list
> Pw_forum at pwscf.org
> http://www.democritos.it/mailman/listinfo/pw_forum




More information about the users mailing list