News:

SMF - Just Installed!

Main Menu

How to eliminate the boundary effect in GEMC simulations?

Started by Jianbo, November 25, 2020, 04:24:53 AM

Previous topic - Next topic

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.