the question of checking atom vector every step and moliere potenial

Dear all,

I have two questions about my model (I want to deposit Platinum atoms on graphite with the effect of Argon):

  1. I want to make a judge every steps when Pt atom are reject back from graphite and reach a hight (z(i) > 20.0 metal unit), I can put this atom in a group and reset the velocity, position and force of this group. I don’t know how to do it, for checking vetor of every atoms every steps and sent them to a dynamic group is a big problem for me.
  2. I want to use Moliere potential between Argon with C and Pt, but I check there is not Moliere potential in lammps, so could you give me some suggestion on potential in lammps about this model?

Thanks so much for your great help!
Best wish!

2011-06-16

Comments below.

Steve

Dear all,

I have two questions about my model (I want to deposit Platinum atoms on
graphite with the effect of Argon):

1. I want to make a judge every steps when Pt atom are reject back from
graphite and reach a hight (z(i) > 20.0 metal unit), I can put this atom in
a group and reset the velocity, position and force of this group. I don't
know how to do it, for checking vetor of every atoms every steps and sent
them to a dynamic group is a big problem for me.

What do you want to do with the atoms when they reach a certain height?
If you want them to just disappear, then use a non-periodic boundary condition.
If you want them reflected back to the surface, then you need a wall
at that position. See the various fix wall commands. You may just want
to use fix wall/reflect.

2. I want to use Moliere potential between Argon with C and Pt, but I check
there is not Moliere potential in lammps, so could you give me some
suggestion on potential in lammps about this model?

I'm not familiar with the Moliere potential. If you can code it up, you can
add it to LAMMPS, like all the other potentials have been. Or you can
tabulate it and use pair table. Or you can find a suitably similar potential
already in LAMMPS and use that.