Can CP2K fixed part of atoms when perform CI-NEB?
jingyu... at gmail.com
Tue Nov 8 16:32:49 CET 2016
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!
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 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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