[CP2K-user] Solid state reaction: suitable decoupling

[Jörg Saßmannshausen]

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