[CP2K-user] Quickstep CUTOFF value for system of liquid water and MTP is too high

[Raghav]

Dear all,

I have a system of 25 A^3 with a methyl triphosphate and liquid water, I 
did cutoff converging calculation following the procedure of the tutorial 
https://www.cp2k.org/howto:converging_cutoff. I'm getting *700 Ry* cutoff 
value for converged energy, which I think is too high. For the gas phase 
system with 30 A^3 box size (only MTP molecule and one water molecule) the 
cutoff value I got was *300 Ry.* 

I think the number of plane waves used in vacuum should be more than the 
liquid phase then why the cutoff value is higher in case of water. My box 
size is smaller for liquid phase though, but still *700 Ry* seems too high.

Could anyone please elaborate on this confusion of cutoff that I have?

I'm using REL_CUTOFF 60 and NGRIDS 4.

Thanks and Regards,
Raghav




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