Problems related to the application of ReaxFF

Hi all,

I want to simulate the interactions between quartz slab and water using ReaxFF, and have several questions:

  1. Is it necessary to difference the O atom in quartz and O atom in water? I noticed that in the LAMMPS examples, they just use same parameters to define these two kinds of O atom.

  2. How to isolate the quartz from the mixtures? I initially make a quartz slab surrounded by water molecules, after the simulation, the quartz slab is still in the water clusters. It is very difficulty to see changes at the surface of quartz. Is there any methods to only output the quartz and the generated “OH” group at the surface?


I don’t believe ReaxFF distinguishes between elements. An O atom is always an O atom.
The ReaxFF input file should have params that make it behave differently depending on
its local environment (in H2O versus quartz).

You can define a group to only dump a subset of atoms. See the dump and dump_modify commands
for a variety of options for how to do it. You can also look at the fix reaxc/bonds command to see
ways to output molecular configs of the current snapshot.