[lammps-users] How to implement 12-7, 12-8, and 12-9 LJ parameters in LAMMPS?

Dears
We would like to simulate a system with Ar and C as a wall. For interaction between wall and fluid “fix wall/lj1043 command” can be used. But we want to use 12-7, 12-8 and 12-9 LJ instead of 12-6 LJ. Is there a way to implement 12-7, 12-8 and 12-9 LJ model in LAMMPS?
Bests

Every best wish from Zanjan
Muhammad Shadman Lakmehsari
Physical Chemistry (Ph.D.),
Associate Professor
The University of Zanjan,
https://www.DrShadman.com
http://zetatext.com

Dears
We would like to simulate a system with Ar and C as a wall. For interaction between wall and fluid “fix wall/lj1043 command” can be used. But we want to use 12-7, 12-8 and 12-9 LJ instead of 12-6 LJ. Is there a way to implement 12-7, 12-8 and 12-9 LJ model in LAMMPS?

you could try using fix addforce with a suitable atom style variable or you would need to modify the source code: https://lammps.sandia.gov/doc/Modify.html

axel.

Dear Prof. Baran
Many thanks
I think mie may can help us.
Let me know if we can hybrid mie and style wall/lj1043 ?

I believe what you are looking for is something similar to the Mie potential.

https://lammps.sandia.gov/doc/pair_mie.html

Best wishes

The hybrid potential is used when you want to combine two different interparticle potentials to achieve features not allowed from just one.
What I assume you want to do is to treat your wall in the system as an implicit one, i.e. no explicit atoms, just a flat wall and its form of interparticle potential.
Therefore there is no need for you to use hybrid potential since you just specify that some type of atoms is interacting with the wall

somehow and others are just being reflected (to avoid overlaps with wall atoms take into account fix wall/reflect as well).

If this is not the case and you want to treat the wall explicitly, you just need to define one additional type of atoms
and specify the interactions for Mie potential with remaining types as you wanted to do with LJ 10/43, i.e. specify those exponents in it, etc…

Best wishes