[Pw_forum] problem with vc-relax

Stefano de Gironcoli degironc at sissa.it
Wed Jan 7 13:19:53 CET 2009


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.
 
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
>
>
>
>       
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