[lammps-users] reax for graphene


I am trying to run simulation of di-vacancy on a graphene sheet using reax. However, I found that the graphene with di-vacancy transformed into a very strange lattice even just using static relaxation. On the other hand, I did the same static relaxation to a perfect grapohene and the structure was stable. Would this possible be a reax force field issue?? I imposed periodic boundary conditions to the in-plane directions of graphene.

Thank you very much!


Aidan - do you want to comment?


Thank you very much for your feedback! I am just wondering if I should use a different reaxFF for pure carbon system. On the other hand, since in the input configuration file of reax must contain charge data, which q value should I put? I assume that this value does not really matter since carbon atoms are neutral in graphite, right?


The version of ReaxFF currently in LAMMPs may not be sufficiently accurate
for graphene sheets. We will be posting several additional versions of
ReaxFf in the near future. For any potential, you should first start by
trying to reproduce some known properties of that potential, then proceed to
your application.

Thank you very much for the information! I am just wondering if the q values (charge) in the input atomic configuration files have any effects on the reaxff simulation of graphite or diamond. I think the carbon atoms in these structures should be neutral (which means q=0 for all carbon atoms), right?


Two comments to that:

First, the input values should have no effect, since LAMMPS will compute the
correct values using the charge equilibration scheme

Second, for a system with only one element, all the calculated charges
should be approximately zero.