[lammps-users] How to get a 6-24 LJ potential in LAMMPS

Hello,

I am wondering how I could get in LAMMPS a 6-26 LJ potential instead of the standard 6-12 or 6-9 ones.

I would like to modify the exponents to get the following potential:

U = 4e[(s/r)^24 - (s/r)^6]

Please note that I cannot modify the lammps code itself since I am not running it on my own machines.

Any help would be greatly appreciated.

Thank you very much in advance

Sincerely,

Thomas Coquil
Research Assistant
UCLA Mechanical and Aerospace Engineering Department
420 Westwood Plaza
43-132 ENGINEERING IV
Los Angeles CA, 90095
Tel: 1 626 429 2110
thomas.coquil@…24…

Hi, Thomas:

I don’t think what you’re asking can be done if you are unable to compile the code yourself. However, in principle, you should be able to compile a version of the code in your personal space and run it from there (that’s what I have to do on most of the machines I work on).

The problem is that the exponents are hard-wired into the code; to change from one value to another, you’d have to go in manually and change everything, and then recompile. (Obviously, it’s better to create a new pair style based off one of the standard LJ potentials and modify that.)

–AEI

Hello,
I am wondering how I could get in LAMMPS a 6-26 LJ potential instead of the
standard 6-12 or 6-9 ones.
I would like to modify the exponents to get the following potential:
U = 4e[(s/r)^24 - (s/r)^6]
Please note that I cannot modify the lammps code itself since I am not
running it on my own machines.

even if you are not running on your own machine, you can always
compile your own version. lammps doesn't use anything that
requires superuser access. i would venture that the most cpu time
with lammps is consumed with self-compiled executables on
machines where people have no root privilege.

that being said, you can model _any_ pairwise additive potential
in LAMMPS using the "table" pair style.

simply generate the files for each interaction pair and run.

cheers,
    axel.