[lammps-users] ReaxFF potential for Graphene Oxide and water

Dear all,

I want to use ReaxFF potential for Graphene Oxide and water system. I’ve created a data file containing the coordinates of all atoms.

But I don’t know how to define the charge for Graphene Oxide atoms, or should I set the charge for these atoms be zero?

For water atoms, I plan to use TIP3P model, that means I’ll use hybrid pair style: ReaxFF potential for Graphene Oxide and LJ potential plus Coulomb force filed for water.

Can it work? Or can I simply use ReaxFF potential for the whole system (three atom types:C, H, O)?

Thanks,
xiongwei

2011/2/20 XIONG <[email protected]>:

Dear all,
I want to use ReaxFF potential for Graphene Oxide and water system. I've
created a data file containing the coordinates of all atoms.
But I don't know how to define the charge for Graphene Oxide atoms, or
should I set the charge for these atoms be zero?

as has been explained a couple of times on this list. the charges
in reax are recomputed in every step, so what you enter in your
data file is only an initial guess. with that in mind, zero should do.

For water atoms, I plan to use TIP3P model, that means I'll use hybrid pair
style: ReaxFF potential for Graphene Oxide and LJ potential
plus Coulomb force filed for water.
Can it work? Or can I simply use ReaxFF potential for the whole system
(three atom types:C, H, O)?

mechanically, yes, both will work. whether it is a meaningful simulation,
that is something else, and depends entirely on what you want to get
out of it and how well the parameterizations match it.

you are missing one important item in your hybrid model, how are you
going to model the interactions between graphite oxide and water itself?
particularly considering that you may have inconsistent charges.

mechanically, yes. whether it is a meaningful simulation,
that is something else, and depends entirely on what you
are hoping to learn from this simulation.

unlike quantum chemical calculations, you have to keep in mind, that
reax parameter sets are not generally transferable, but created for class
of compounds.

cheers,
    axel.