improper definition to lammps

hi all
i have a problem with improper definition to lammps .I have a improper between i,j,k and l atoms (atom l moves out of plane). how can I define it to the lammps? I mean the order of atoms for definition (i, j ,k , l ) or (j, i, k , l) or ( i , k , j ,l) or something else.
thanks dear friends

I’m not sure if this is an accidental double-posting (somehow an hour later), but if it was not accidental, it’s considered poor manners to send the same question to the list in a short period of time. Spamming the list is the fastest way to annoy people (and make them less likely to answer your question or future questions).

By the way, I answered your question in the first email. To expand on my answer, this is how impropers are written (taken from one of my data files):

19232 6 11554 11558 11559 11563
19233 6 11554 11558 11559 11564
19234 5 11554 11558 11563 11564
19235 5 11559 11558 11563 11564

The first number is the ID of the improper, the second number is the type of improper, and the last four numbers belong to the atom IDs in the improper. As you can see here, 11558 is the atom which moves out of plane.

Hope that helps,

Also, to clarify, the format I showed is the class2 improper style. As Andrew mentioned in a different thread, the order of the improper can change between styles.

thank you dear will
how did you build the data file with what software? i make it by msi2lmp code for class 2 forcefield (pcff) but the moving atom is the last one as you see:

Improper Coeffs # class2

1 51.6374 0.0000 # oz-cz-oz-oo

but the moving atom is the last one (oo is the forcefield name of carbonyle oxygen in ethylene carbonate molecule)


thank you .

I use an in-house code developed by my PhD research group. It also uses msi2lmp. Unfortunately, I do not have permission to share the code.