[gmx-users] Graphene Sheet Rolling up into CNT

[Darrell Koskinen]

Hey GROMACS Gurus,
I was wondering if you could enlighten me. I performed a simulation of a 
graphene sheet in an ammonia gas at 240K using ffoplsaa parameters and 
see that the graphene sheet begins to curl up into what appears to be a 
nanotube. I did not run the simulation long enough to actually see it 
form a nanotube, but it appears to be headed in that direction. I am not 
sure if a graphene sheet would actually curl up on itself to form a CNT 
at this temperature. I believe CNTs are formed by ablation of pure 
graphite and therefore rolling up a graphene sheets must occur for the 
CNTs to form, but assumed that the local temperature increase resulting 
from the ablation was the cause of the rolling up. So I am wondering if 
you might be able to give me some idea of why this is happening? Could 
it be that the OPLS LJ parameters, since OPLS was created for liquids 
and not gases, are creating forces too great for a gaseous simulation 
thus causing too great an attraction between distant carbon atoms within 
the graphene lattice, which manifests itself in the rolling up of the 
graphene into a CNT? Or could the curling up be occurring because the 
graphene sheet is free floating in space as would happen during 
ablation. Maybe rolling up of graphene sheets does occur at such a low 
temperature. I will do some research on this possibility, but in the 
mean time please provide me your comments, if you can.

Thanks.

Darrell