Fix gcmc and fix rigid/nvt/small with multiple molecule templates

LAMMPS LAMMPS Development
1

Hi, I am trying to simulate competitive adsorption of a binary mixture of gas in a porous medium using GC+MD in LAMMPS. My system has a gas reservoir and a porous film. Number of molecules in the reservoir are controlled using gcmc and the time integrations are performed with fix rigid/nvt/small.

Relevant lines from my script are:

compute mdtemp gas temp
compute_modify mdtemp dynamic/dof yes

fix mygcmc1      gas gcmc 20000 10 0 0 987987 ${tem} ${mu} ${dis} region res mol co2mol pressure ${pr1} full_energy tfac_insert 2 rigid myrigid

fix myrigid gas rigid/nvt/small molecule temp ${tem} ${tem} ${Tdamp} mol co2mol
fix_modify myrigid temp mdtemp
fix_modify myrigid dynamic/dof yes

This works fine with a single molecule template (here co2mol). It seems that these two fixes only accept a single molecule template as input and they must match with each other. My question is- Is there any other way to maintain communication between fix gcmc and fix rigid/nvt/small using two or more molecule templates?

Any help would be appreciated. Thank you.

2

Not unless you are ready to modify the source code for both of them accordingly.
You could try having two instances of fix rigid/small and fix gcmc, but there are well known problems with that.

Overall, I suspect that your project is beyond the MC capability of LAMMPS (which was designed as an MD code and MC capabilities have been added on and cause increasing problems and inefficiencies the more complex and demanding the MC components get) and you would probably better off using a proper MC code for running your simulations.

3

Hi Axel,

Got your point. Thanks you!

Regards
Pritom