[CP2K-user] [CP2K:16538] Re: Prevent Cell Geometry/Vectors From Changing

[fabia...@gmail.com]

I've never used &BAND together with &CONSTRAINT. From a quick glance at the 
source code I think that it might not be implemented.

On Tuesday, 1 February 2022 at 08:45:34 UTC+1 lenardc... at gmail.com wrote:

> Hey Fabian, I'm messaging here since I didn't get a response on my other 
> question. What about NEB calculations, what do I do there if I don't want 
> the fixed atoms to move?
>
> On Tuesday, January 25, 2022 at 1:24:01 PM UTC+2 ASSIDUO Network wrote:
>
>> Great, thanks for letting me know. 
>>
>> On Monday, January 24, 2022 at 3:24:58 PM UTC+2 fabia... at gmail.com wrote:
>>
>>> No, for MD the ensemble type determines if the cell dimensions are fixed 
>>> or not: 
>>> https://manual.cp2k.org/cp2k-9_1-branch/CP2K_INPUT/MOTION/MD.html#ENSEMBLE
>>> The cell only changes if you choose NPT, otherwise it is fixed.
>>>
>>> Fabian
>>>
>>> On Monday, 24 January 2022 at 08:46:45 UTC+1 lenardc... at gmail.com wrote:
>>>
>>>> Thanks for feedback Fabian, I appreciate it. Does the above also apply 
>>>> to AIMD simulations where you have the
>>>> &MOTION
>>>>   &GEO_OPT
>>>>   &END
>>>> &END
>>>> section still included?
>>>> On Thursday, January 20, 2022 at 2:20:26 PM UTC+2 fabia... at gmail.com 
>>>> wrote:
>>>>
>>>>> Hi Lenard,
>>>>>
>>>>> in cp2k there are two types of optimizations, GEO_OPT and CELL_OPT. In 
>>>>> GEO_OPT the lattice vectors are fixed and only the atomic positions are 
>>>>> optimized. In a CELL_OPT both the lattice vactors and the atomic positions 
>>>>> can be relaxed simultaneously.
>>>>>
>>>>> So if you don't want the box to change you need 
>>>>> RUN_TYPE GEO_OPT 
>>>>> and  the
>>>>> &MOTION
>>>>>   &GEO_OPT
>>>>>   &END
>>>>> &END
>>>>> section.
>>>>>
>>>>> If the SCF does not converge the forces (and pressure) are probably 
>>>>> very bad and thus the optimizer (e.g. BFGS) takes unreasonable steps. If 
>>>>> the SCF does not converge you should probably stop the simulation and 
>>>>> improve SCF stability.
>>>>>
>>>>> Cheers,
>>>>> Fabian
>>>>> On Thursday, 20 January 2022 at 05:50:59 UTC+1 lenardc... at gmail.com 
>>>>> wrote:
>>>>>
>>>>>> Hi there. So, I've been doing a few geometry optimizations and I have 
>>>>>> seen that for some of them, the cell vectors change, sometimes a bit other 
>>>>>> times a lot. This especially happens when the SCF run is not converged 
>>>>>> multiple times in a row. The thing is, I don't want the cell vectors to 
>>>>>> change, I don't want the atoms to go outside of the box, yet it still 
>>>>>> happens. Can you give me any tips/ideas on how to do a geometry 
>>>>>> optimizations where atomic positions can only change and the cell geometry 
>>>>>> cannot, or is this not feasible?
>>>>>>
>>>>>> Kind regards,
>>>>>> Lenard
>>>>>>
>>>>>

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