Combining potentials of classical

[Aun]

We can use combining different potentials only Tersoff and Lennard Jones. Hope to use other different potential such as Reaxff and EAM.

[Julian Schneider]

In principle you can combine all potentials, not only Lennard Jones and Tersoff.
There are some limitations for EAM and ReaxFF, which means that a ReaxFF or EAM potential cannot be used for only a part of the configuration, but they must be defined for all atoms in the system (for EAM one can make a workaround, if necessary).
Still, other potentials, such as Lennard Jones, can be added to a ReaxFF or EAM potential, as well.

[Aun]

Thank for your explaination.
It means that Reaxff potential will be applied to all atoms according to added particals to potential set and also possible adding Lennard Jones potential to these particles even though Reaxff is not be able  to apply for only specified location of atoms using tags. What I would like to confirm is Reaxff will be effect only particles which are added to Reaxff potential set. Is that right?

[Julian Schneider]

You cannot select particle types when you set up a ReaxFF potential (see http://docs.quantumwise.com/manuals/Types/ReaxFFPotential/ReaxFFPotential.html#reaxffpotential-c). It automatically acts on all particles in the system, meaning that the reax parameter file must contain parameters for at least all elements in the configuration.
If you wanted the potential not to act on some of the elements, you would have to add these as dummy elements with zero interaction to the reax parameter file.

Once you have set up a ReaxFF potential for your entire system, you can add (almost) any other potential on top of the ReaxFF potential to extend the potential if necessary.