Pulling graphene

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Hello Everyone,

I want to find the pull out of functionalized graphene filled with polymer. In order to achieve the final objective. I have started simulation with single graphene at 0.01 K to with non periodic boundary conditions in pulling direction. I am using ReaxFF force field. I need some suggestions

1st Method: I will select a few atoms at corners of graphene and assign a group say movingatoms. I will displace it a certain distance and freeze this group using setforce command available in LAMMPS, and run NVE time integration and repeat again and again. But in this case there are chances of breaking of graphene.

2nd Method: I will select all atoms of graphene and displace it a few distance. Then , select few atoms at corner of graphene and assigned group and apply setforce 0 0 0 on atoms belong to this group. Then, run NVE to calculate energy on all atoms. And repeat again from starting.

Which one should I prefer as later on I have functionalized graphene?

Thanks and Best Regards,
Ankit,

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3rd method: apply fix smd to all graphene atoms
4th method: apply fix move to all or some graphene atoms (and no other time integration to those)
5th method: assuming to pull in z-direction, apply fix setforce NULL NULL 0.0, set an explicit velocity on those atoms in z-direction (but keep the rest as is) and do regular time integration (that way the sheet has a forced motion in z but is free to move in x and y). if using a thermostat, for that you need to define a custom temperature compute, like compute temp/partial 1 1 0

there are likely a few more variants or hybrids of the listed versions. which one is the most suitable depends on the specifics of your model and what you want to learn from it. you may want to discuss with your adviser. in general, the purpose of this list is primarily to discuss the technical aspects of how to setup and use LAMMPS, not so much what is the best way to do your science.

axel.