Why can't cell optimization converge?

Matthias Krack matthia... at psi.ch
Mon Mar 3 11:14:13 UTC 2014

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?



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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