Author Topic: Different cutoff for vapor and liquid boxes in Gibbs ensemble MC  (Read 587 times)

ssharlin

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Hi,

I just started learning RASPA and I am trying to set up a Gibbs Ensemble VLE, the previous software I used (MCCCS-MN) allowed me to have a different cut-off length for vapor and liquid boxes. I was trying to use 2 different ones where the box is defined in the simulation input file for Raspa.. but it seems like it only reads it from the Force Field definition sections and can take only a single value for both the boxes. Is there a way to work around that?

David Dubbeldam

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Re: Different cutoff for vapor and liquid boxes in Gibbs ensemble MC
« Reply #1 on: June 30, 2022, 10:01:15 AM »
The 'CutOffVDW' should not be different for the gas and liquid phase, otherwise you're using different force fields for them.
The 'CutOffCoulomb' should be set to something slightly smaller than half the box size. This significantly speeds up the computation for the gas-phase since the gas-phase box can be large.
Importantly, both can be set per system (just list them after the 'Box' statement).

ssharlin

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Re: Different cutoff for vapor and liquid boxes in Gibbs ensemble MC
« Reply #2 on: June 30, 2022, 10:36:15 PM »
Thank you, Dr. Dubbeldam. It's nice that we can set up both VDW and Coulomb cutoffs individually in RASPA!