Accessing Dummy Point of TIP4P Potential?

Dear all,

I am using LAMMPS 16Feb16 to simulate an water-ice slab interacting with a single H_2 Molecule. I am running a hybrid potential such that the water molecules interact via a TIP4P potential and the H_2 interacts with the water molecules via a modified LJ 8/6 + Coul potential.

There are 4 terms for this LJ 8/6 + Coul interaction, one for each atom in the water molecule and then one for the dummy point in between the two hydrogen atoms (see the appendix in “Intermolecular potential of H2O . . . H2 in the van der Waals region. An ab initio study” by Zhang et al. 1992 for the specific form). Is there a simple way for me to specify the interaction between the H_2 molecule and this dummy point in the water molecule?

I have seen cases where it was suggested to physically put in the dummy point and treat the water molecules as rigid, but if possible I would like to avoid this fix.

Thanks so much for the help,

John

Dear all,

I am using LAMMPS 16Feb16 to simulate an water-ice slab interacting with a
single H_2 Molecule. I am running a hybrid potential such that the water
molecules interact via a TIP4P potential and the H_2 interacts with the
water molecules via a modified LJ 8/6 + Coul potential.

There are 4 terms for this LJ 8/6 + Coul interaction, one for each atom in
the water molecule and then one for the dummy point in between the two
hydrogen atoms (see the appendix in "Intermolecular potential of H2O . . .
H2 in the van der Waals region. An ab initio study" by Zhang et al. 1992 for
the specific form). Is there a simple way for me to specify the interaction
between the H_2 molecule and this dummy point in the water molecule?

simple? no.

I have seen cases where it was suggested to physically put in the dummy
point and treat the water molecules as rigid, but if possible I would like
to avoid this fix.

i don't see any other way outside of programming a custom pair style.

axel.