Can CP2K fixed part of atoms when perform CI-NEB?

Matthias Krack matthia... at psi.ch
Tue Nov 8 09:12:42 CET 2016


Hi

do you have any special reason to use the OPT_TYPE MD? Otherwise I suggest 
to try the default OPT_TYPE DIIS which should be much more efficient. 
Moreover, if you want to fix some atoms only because of the computational 
cost caused by the large size of your system then there will be most likely 
not much benefit doing so, because the forces for all atoms are calculated 
anyway and then set to zero for the fixed atoms afterwards. You should 
rather check if fixing atoms is really needed as a boundary for a realistic 
modelling of the reaction you are interested in.

Best regards

Matthias

On Tuesday, 8 November 2016 07:01:18 UTC+1, J. Ye wrote:
>
>  Hi Fabio, 
>
> I indeed included both "ALIGN_FRAMES FALSE" and "ROTATE_FRAMES FALSE" in 
> my input(Please see the attachment). But I still found the atoms moves. The 
> methods we use are different. I don't know how does this affect the fixed 
> atoms. Do you have any idea? 
>
> I have tested your input. Atom 1 and 3 indeed do not move. I also tried to 
> switch TI-NEB to CI-NEB, the atoms are not move. So this should not be 
> affected by BAND_TYPE. 
>
> Can any expert of CP2K give us some hints on this problem? 
>
> Thanks very much!
> Best,
>
> J. Ye
>
> On Monday, November 7, 2016 at 2:02:05 PM UTC-6, elb... at gmail.com wrote:
>>
>> Hello J. Ye!
>>
>> Yes, I have checked. If you use only the constraint flag, indeed the 
>> fixed atoms move for the other images. But if you include both 
>> "ALIGN_FRAMES FALSE" and "ROTATE_FRAMES FALSE" flags in the BAND section, 
>> that does not happen anymore, at least in the calculations I have performed 
>> so far. Check for example the NEB input attached to this e-mail. It is very 
>> simple and it runs very fast (it has no meaning, it is just an example), 
>> but you can check that atoms 1 and 3, that are asked to be fixed, do not 
>> move for all NEB images. Let me know if you get the same behavior as me!
>>
>> All the best!
>>
>
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