Why can't cell optimization converge?

Enlong Liu liuen... at gmail.com
Mon Mar 3 11:36:48 UTC 2014

Dear Matthias,

By using LBFGS, the simulation stops in 27 steps and the result is better 
than I got after 1000 steps. But I still can not be sure whether it is 
finally optimized. However, thank you very much! I think it works very well.

Best regards,

在 2014年3月3日星期一UTC+1下午12时14分13秒,Matthias Krack写道:
> Dear Enlong,
> either you provide a full setup (i.e. including the atomic coordinates) 
> for the actual case, or you provide the input and the corresponding output 
> file (at least part of it) showing the problem.
> Did you try LBFGS?
> Best,
> Matthias
> On Monday, March 3, 2014 11:57:27 AM UTC+1, Enlong Liu wrote:
>> Dear Matthias,
>> Thanks!
>> But I find out that the input I upload is a wrong one. So maybe you can 
>> have look at the right one and give me some suggestion. 
>> Best regards,
>> Enlong
>> 在 2014年3月3日星期一UTC+1上午11时12分52秒,Matthias Krack写道:
>>> Dear Enlong,,
>>> I would suggest to use BFGS (or LBFGS for large systems) instead of CG. 
>>> Moreover, you may change the PRINT_LEVEL to medium to get more info. 
>>> However, even if the run will converge somehow, the results won't be 
>>> reasonable given the cell size of only 2.5A in z direction in a gamma point 
>>> calculation.
>>> Matthias
>>> On Monday, March 3, 2014 10:41:11 AM UTC+1, Enlong Liu wrote:
>>>> Fellows,
>>>> I am practicing CP2K by doing cell optimization and geometry 
>>>> optimization to CNT. In the cell_opt, I choose 'DIRECT_CELL_OPT*: 
>>>> Performs a geometry and cell optimization at the same time. The stress 
>>>> tensor is computed at every step* '. And the max SCF iteration is 
>>>> 1000. However, every time I run the program, the program always used all 
>>>> 1000 iteration to get the result, which in my opinion, means the result 
>>>> does not converge. It seems like for every step, the threshold for energy 
>>>> is satisfied but between steps the threshold for geometry can not be 
>>>> satisfied. Could you help me to solve this issue?
>>>> PS: the input file is in the attachment.
>>>> Thanks a lot for your help!
>>>> Best regards,
>>>> Enlong
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