[CP2K-user] [CP2K:16491] Re: Prevent Cell Geometry/Vectors From Changing

[ASSIDUO Network]

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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