How to make attractive force zero to certain group of atoms

Dear Lammps users,

Good day! I have come to know that I can make the attractive force (LJ potential) zero by setting cutoff 2^(1/6)*sigma to the system and setting “pair_modify shift yes”. However, if I want to make the attractive force zero for a certain group of atoms of my total system, how can I accomplish the task?

As for example I have 10K atoms and I want the attractive force to become zero only for first 5K atoms.

Thanks a lot!

Dear Lammps users,

Good day! I have come to know that I can make the attractive force (LJ
potential) zero by setting cutoff 2^(1/6)*sigma to the system and setting
"pair_modify shift yes". However, if I want to make the attractive force
zero for a certain group of atoms of my total system, how can I accomplish
the task?

just have multiple atom types and set the cutoff accordingly per pair
of types. for details please read the documentation for the commands
pair_style, pair_coeff and pair_style lj/cut very carefully.

axel.