Dear Altruists
I am a new user in LAMMPS and I am trying to do a simulation for graphene and CO2 system. My system contain 100 CO2 and one bi-layer graphene. I want to observe the adsorption phenomenon of CO2 on graphene. However, when I run simulation without fixing or making rigid the structure of the graphene I can found some of the CO2 molecules are adsorbed on graphene. But when I use
fix 2 graphene1 setforce 0.0 0.0 0.0
fix 3 graphene2 setforce 0.0 0.0 0.0
comments for fix the graphene in a place, then I could not found any kinds of adsorption phenomenon. What kinds of mistake I made? could any please help me to resolve it?
Any kinds of suggestion will be good for me
Thanks in advance
Regard
Sharif Khan
Setting forces in all directions, makes the Graphene layer hard and frozen. Everytime, the 'fix setforce' command is called, the velocity is made zero -> position of atoms in next timestep don't change -> Potential change is zero. But when another atom comes in contact with an atom, the potential should change (increase or decrease depending on the repulsive or attractive force). Since, the force is set zero, its neither attracting nor repulsing the adsorbing atoms.
You can try using 'minimize' command on Graphene layers instead of setting all forces to zero.
I suggest using REBO Potentials(http://iopscience.iop.org/article/10.1088/0953-8984/14/4/312/meta) for the graphene CO2 interaction and fix a single carbon atom of each sheet so that the sheets would not move out of position.
See:http://lammps.sandia.gov/doc/pair_airebo.html
I use another simulation software.
What I do in graphene sheets, is to fix the position of only one C atom. Since the boundary conditions are 3D periodic, the fixed C atom limits the translation of the graphene (but allows vibrations).
- Badges
- Science topic
- Similar topics
- Physical Sciences
- Materials Science
- Materials
- Carbon Materials
- Graphite
- Graphene