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

[Lenard Carroll]

Thanks for letting me know Fabian, I appreciate it.

On Tue, Feb 1, 2022 at 11:04 AM fabia... at gmail.com <fabianducry at gmail.com>
wrote:

> 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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