[CP2K-user] QMMM energy conservation problem

[Бранислав Миловановић]

Dear cp2k users/developers,

I'm trying to simulate DNA guanine quadruplex using QMMM approach. MM force 
field parameters are prepared with AmberTools20. QM part is constituted of 
Na+ cation coordinated by 8 guanine molecules (so called G-octet), while 
other nucleobases, counterions and solvating water molecules are treated 
with MM.

System was previously equlibrated with NVT ensemble and MM approach with no 
problem encountered. Also, when I try to run QM part of the system only 
using same DFT settings as in the case of QMMM calculation I have no 
problems.

However, when I try to run QMMM calculation under present setup (input 
files in the attachment) I constantly get shift of the Cons Qty during my 
run, for both NVE and NVT runs (graphs from my last attempt are in the 
attachment).

I tried different calculation setup (different timestep, ewald summation 
parms etc.) by looking to the previous topics here in the group but with no 
success.

Maybe there is something trivial bothering me here, qmmm link settings or 
similar...
I used IMOMM method for the link and also distributed charges across 
neighbouring MM atoms to neutralize MM subsystem.

Can anybody help me with this?

Kind regards,
Branislav

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