iRASPA Community
RASPA => General => Topic started by: Jianbo on November 25, 2020, 04:24:53 AM

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

Boundary effects are already eliminated in the grandcanonical and Gibbs approach.
For the grandcanonical 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 finitesize effects.

Dear Dubbeldam,
Thanks for your reply. It seems I misused the two effects, i.e. the boundary effect and the finitesize effect.
In the grandcanonical approach, the intermolecular force between the substrate of interest and the image substrate can be minimized by creating the free space in the zdirection. In other words, the finitesize effect can be handled.
However, for the Gibbs approach, if the simulation box of the adsorbed phase is enlarged to avoid the finitesize 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

Do you mean that you want to simulate adsorption on the outside of the zeolite?
Because using the grandcanonical approach only the adsorbed phase inside the framework is computed.
I have no experience with adsorption on the external surface of a zeolite.