Regarding the COMB3 Potential

Hi Lammps Users,

I am trying to build a system with 5 type of atoms: Cu,Cu,H, Cu O. Among these 5 types the first 3 types don’t have any charge, while the remaining Cu and O atoms have charge( As CuO). So Can I use COMB3 potential for my whole system setting zero charge for the first 3 types of atoms and +2 and -2 for rest? Thanks in advance.

Best Regards,
Joy Acharjee

Hi Lammps Users,

I am trying to build a system with 5 type of atoms: Cu,Cu,H, Cu O. Among these 5 types the first 3 types don't have any charge, while the remaining Cu and O atoms have charge( As CuO). So Can I use COMB3 potential for my whole system setting zero charge for the first 3 types of atoms and +2 and -2 for rest? Thanks in advance.

please study the documentation and the publications referenced in it.
for example the docs say:

The COMB potentials (styles {comb} and {comb3}) are variable charge
potentials. The equilibrium charge on each atom is calculated by the
electronegativity equalization (QEq) method.

so whatever you put into your input as charges will be only considered
a starting point for the following charge equilibration and likely
most atoms will have (different, partial) charges depending on their
environment.

axel.

Dear Mr. Axel,

Thanks a lot for your reply. So should when We have a system having atoms with and without charge what should we do? Use the hybrid pair_style? Thanks again!

Dear Mr. Axel,

Thanks a lot for your reply. So should when We have a system having atoms with and without charge what should we do? Use the hybrid pair_style? Thanks again!

first thing is to read and _understand_ the COMB/COMB3 papers so you
understand how these potentials work. your question indicates, that
you don't understand. there is no point in me trying to give you
advice unless you do.

axel.