Can CP2K fixed part of atoms when perform CI-NEB?
jingyu... at gmail.com
Tue Nov 8 17:12:41 CET 2016
I have another question. The default value for CONVERGENCE_CONTROL
BAND optimization is very difficult to converge. I was curious is why the
criterias for BAND optimization is so high? What is the reasonable
On Tuesday, November 8, 2016 at 9:32:49 AM UTC-6, J. Ye wrote:
> Hi Matthias,
> I am working on a catalyst material that has metal nanoparticles supported
> on a porous material. This porous material which is a big system that has
> about 600 atoms, however the catalytic reaction process only on the metal
> clusters. We want to study the effect of the pore size on the catalytic
> reaction. So I want to perform a periodic calculations and compare with
> cluster model. If the barriers are similar, then I could perform for
> cluster model instead.
> Your suggestion is peroform QM/MM?
> What's the difference between DIIS and MD? Why DIIS is more efficient? Do
> you have any books or papers recommend for us to read?
> Thanks very much!
> Best regards,
> J. Ye
> On Tuesday, November 8, 2016 at 2:12:42 AM UTC-6, Matthias Krack wrote:
>> 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
>> 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!
>>> J. Ye
>>> On Monday, November 7, 2016 at 2:02:05 PM UTC-6, elb... at gmail.com
>>>> 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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