Author Topic: Density by NPT MC and MD  (Read 455 times)

ae213

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Density by NPT MC and MD
« on: August 03, 2020, 12:35:07 AM »
Dear Prof. Dubbeldam and RASPA users,

I was trying to calculate the density of the bulk liquid using NPT ensemble with MC and validate by NPT MD simulation.
I am using the same force field and the rest of the parameters for the molecule. I got the expected result (close to the experimental value) with MC which also agrees well with MD simulation in LAMMPS. However, MD result by RASPA is much higher (about 60 kg/m3 difference). Both results were well equilibrated.
I was trying to turn on/off tail correction and change the time step, and it did not change the result significantly.
What may be the reason of this discrepancy?

dubbelda

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Re: Density by NPT MC and MD
« Reply #1 on: August 20, 2020, 12:18:20 PM »
MD always uses a shifted potential. Did you use the same in the Monte Carlo?
Did you use appropriate MC moves like translation, rotation, reinsertion, partial reinsertion to sample to the phase-space properly?