GCMC results not exactly matching with literature

[Vardhan]

Respected Prof. Dubbeldam

I am trying to replicate the adsorption isotherm on a zeolite, from the literature. In the literature, they have used Gibbs ensemble to study the adsorption on a zeolite. Using GCMC in RASPA, I tried to replicate the same thing. However, I am getting lower values compared to the literature. A constant difference of 0.5 mmol/g is being obtained at all pressures (0.1 bar to 10 bar). All the force fields, molecule models, and structure are the same. Could the difference in the ensemble, (or difference in the code) be the reason for this difference of 0.5 mmol/g?

Thanks and regards

[David Dubbeldam]

That could be for a variety of reasons, including slightly different positions for the atoms of a rigid molecule, and details like cutoff-distance, tail-corrections yes/no, etc. Also, results depend on the total amount of molecules and the system size etc.

[Vardhan]

Dear Professor,

Thanks for the swift reply. As I have mentioned earlier, the simulation box size (number of unit cells in x y z directions), cutoff-distance, tail corrections, force fields, etc., all were the same. The framework structure was also taken from the same reference.  The only difference I could find is the type of ensemble (Gibbs ensemble vs GCMC). Could this be the reason? Can this have a difference of 0.5mol/Kg?

Thanks and regards