How to eliminate the boundary effect in GEMC simulations?

[Jianbo]

Dear RASPA users,

I want to simulate the adsorption of water on zeolites via Gibbs ensemble Monte Carlo (GEMC) simulation.

In a Grand Canonical Monte Carlo (GCMC) simulation, I can create a free space of several hundred Å to eliminate the effect.

However, it seems impractical to do the same in a GEMC simulation.

Thus, how can I eliminate the influence of image zeolites on water?

Thanks in advance
Sincerely,
Jianbo Wang

[David Dubbeldam]

Boundary effects are already eliminated in the grand-canonical and Gibbs approach.
For the grand-canonical approach, only the adsorbed phase is simulated.
For the Gibbs approach, the adsorbed phase and a fluid phase is simulated.
In both there are no surface effects. You do need sufficiently large systems to minimize finite-size effects.

[Jianbo]

Dear Dubbeldam,

Thanks for your reply. It seems I misused the two effects, i.e. the boundary effect and the finite-size effect.

In the grand-canonical approach, the intermolecular force between the substrate of interest and the image substrate can be minimized by creating the free space in the z-direction. In other words, the finite-size effect can be handled.

However, for the Gibbs approach,  if the simulation box of the adsorbed phase is enlarged to avoid the finite-size effect, a fluid phase seems to appear in this simulation box.

So, is it practical to set the adsorbed phase box with a sufficiently large box volume?

Thanks in advance
Sincerely,
Jianbo Wang

[David Dubbeldam]

Do you mean that you want to simulate adsorption on the outside of the zeolite?
Because using the grand-canonical approach only the adsorbed phase inside the framework is computed.

I have no experience with adsorption on the external surface of a zeolite.