[CP2K-user] Creating/Finding a small but realistic MD model for my research

[Tue Boesen]

I have played around with cp2k over the last few days and I have come up 
with the following MD simulation of aspirin, however there are still a 
bunch of things that I'm uncertain about and would like some input on:

*Is the basis set sufficient?* I use the HFX_BASIS, which I found in some 
excercises, but I don't know whether this is good enough for an actual 
model or only used when learning to use cp2k.
*Poisson solver?* My model does not have periodic boundary conditions, so I 
have to choose a poisson_solver, I chose implicit, but I have no idea 
whether this is sensible?
                             Furthermore, I found the following in some 
other MD simulation without periodic boundaries, and was wondering whether 
I should include something like this as well (not really sure what this 
does though)
      &EWALD                    ! This section specifies parameters for the 
EWALD summation method     
        EWALD_TYPE ewald            ! Standard non-fft based ewald method
        ALPHA .36
        GMAX 29                    ! Number of grid points
      &END EWALD

*Thermostat: *Previous simulation of Aspirin used Nose-Hoover thermostat, 
however I couldn't figure out how to implement that so for now I use GLE, 
but is that okay, and is it set up properly for such a small system?
*Box size:* Right now I'm just using a regular box of 12.42 for my 
simulation but maybe that isn't appropiate?

*Additional: *I remember reading something about how you shouldn't trust 
the early parts of a simulation, but I can't find it again. If I run the 
above, would I need to throw away parts of the simulation and if so how 
much?

Anything else I would need to do/change before running this simulation 
would be greatly appreciated.

Kind Regards
Tue

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