[CP2K:4868] Re: optimization problem of a supercell

[Ari Paavo Seitsonen]

Dear Mohamed,

  Please notice that the timing of your question is not the optimal - for
example our University is closed around these days, thus few colleagues
that might be potential respondents are not at work. And your question is
not very easy, at least without the input and output (at least the
geometry, to understand how large the deviations are).

  My uneducated guess is that the convergence criteria and numerical
parametres cause the symmetry to break somewhat. In many other codes the
symmetry is imposed and held fixed during the relaxation, but this is not
the case in the case of CP2K. If there is no physical reason why the
symmetry might be lowered, you could try increasing the accuracy and seeing
if the deviation in the structural quantities is reduced.

    Greetings from Zurich,

       apsi


2013/12/31 mohamed khuili <khuili... at gmail.com>

> *No reply!!!*
>
> Le lundi 30 décembre 2013 13:20:58 UTC, mohamed khuili a écrit :
>
>>
>> <https://lh3.googleusercontent.com/-vla8hI4PRNc/UsFzJ_ueSaI/AAAAAAAAAFM/0K5kIkp6qQk/s1600/syst.png>
>> hello, happy new year
>> I ask you to help me find the solution to my problem of optimization:
>> my problem is when the program completes successfully optimizing I find most
>> of the atoms are not linked to each other, and the Zn-O distances Zn-Zn
>> and OO are not the same in the supercell.
>> you find attached the image before and after optimization
>>
>>
>>
>>
>>  --------  Informations at step =   140 ------------
>>   Optimization Method        =                 BFGS
>>   Total Energy               =     -1225.3956552841
>>   Internal Pressure [bar]    =       124.0112044496
>>   Real energy change         =        -0.0000027184
>>   Predicted change in energy =        -0.0000010497
>>   Scaling factor             =         0.2686282801
>>   Step size                  =         0.0015580487
>>   Trust radius               =         0.4724315332
>>   Decrease in energy         =                  YES
>>   Used time                  =              140.367
>>
>>   Convergence check :
>>   Max. step size             =         0.0015580487
>>   Conv. limit for step size  =         0.0030000000
>>   Convergence in step size   =                  YES
>>   RMS step size              =         0.0003676384
>>   Conv. limit for RMS step   =         0.0015000000
>>   Convergence in RMS step    =                  YES
>>   Max. gradient              =         0.0003428922
>>   Conv. limit for gradients  =         0.0004500000
>>   Conv. in gradients         =                  YES
>>   RMS gradient               =         0.0000829366
>>   Conv. limit for RMS grad.  =         0.0003000000
>>   Conv. in RMS gradients     =                  YES
>>   Pressure Deviation [bar]   =        24.0112044496
>>   Pressure Tolerance [bar]   =       100.0000000000
>>   Conv. for  PRESSURE        =                  YES
>>  ---------------------------------------------------
>>
>>  ***********************************************************
>> ********************
>>  ***                    GEOMETRY OPTIMIZATION
>> COMPLETED                      ***
>>  ***********************************************************
>> ********************
>>
>> thank you
>>
>>
>>  --
> You received this message because you are subscribed to the Google Groups
> "cp2k" group.
> To unsubscribe from this group and stop receiving emails from it, send an
> email to cp2k+uns... at googlegroups.com.
> To post to this group, send email to cp... at googlegroups.com.
> Visit this group at http://groups.google.com/group/cp2k.
> For more options, visit https://groups.google.com/groups/opt_out.
>



-- 
-=*=-=*=-=*=-=*=-=*=-=*=-=*=-=*=-=*=-=*=-=*=-=*=-=*=-=*=-=*=-=*=-=*=-=*=-=*=-
  Ari P Seitsonen / Ari.P.S... at iki.fi / http://www.iki.fi/~apsi/
  Physikalisch-Chemisches Institut der Universität Zürich
  Tel: +41 44 63 55 44 97  /  Mobile: +41 79 71 90 935
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <https://lists.cp2k.org/archives/cp2k-user/attachments/20131231/1638e956/attachment.htm>