[CP2K-user] Solid state reaction: suitable decoupling

[Luca]

Dear Jörg,
maybe, I did not understand  the question; 
if you "decouple the cell" with MT scheme you are going to model the system 
in gas phase like in GAMESS.
Anyway, if you do not use periodic system, you have to check that electron 
density goes to zero prior to the cell border.
When I study a reaction with cp2k, and I need to  characterize the TS, I 
use dimer-method or NEB. 
If I need to model the system in gas phase
(no periodic system) and the system is "spheric-like", 
I prefer to use  WAVELET.
I hope it is helpful to you.
Cheers,

Luca



Il giorno domenica 13 dicembre 2020 alle 12:26:24 UTC+1 sassy ha scritto:

> Dear all, 
>
> I am normally calculating molecules in the gas phase, so my knowledge of 
> cp2k 
> is still a but rusty as I don't use it as much as I would love to. 
>
> I am currently looking into an observed solid state reaction of the type: 
>
> A -> B + C 
>
> We got an x-ray of A and we observe the product B + C per x-ray as well as 
> a ~ 
> 10% "contamination". 
> If I am using the usual DFT tools like GAMESS-US or Gaussian and put the 
> coordinates of A + B in the input file, they are flying away from each 
> other. 
> That makes sense in the gas phase but not in the solid state. 
> Thus, I thought of calculating the unit cell in cp2k which should mimic 
> better 
> the conditions where we are observing the products. 
>
> I was thinking of using PBE-D3 for that, together with the Molopt basis 
> set 
> which was working well for me in other calculations I done before. 
>
> I am a bit unsure regarding the affect the size of the cell and which 
> decoupler to use. I usually go for MT but as there has been quite some 
> development recently it seems, I am not sure if that is still the best 
> current 
> advice. 
>
> For example, what will happen if for my specific problem I make the cell a 
> bit 
> bigger than what you usually would do for the chosen decoupler? 
>
> The overall aim of the project is more ambitious, I want to model the 
> reaction 
> path of this reaction if that is possible. However, that is for the 
> future. 
>
> Any suggestions are much appreciated. 
>
> All the best from Lyttle Britain. 
>
> Jörg 
>
>
>
>
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