Dear Dr. Axel Kohlmeyer,
Hello Dr. Kohlmeyer. I was curious if I could ask one question on pair_style hybrid command.
I have Type 1, Type 2 and Type 3 atoms in my simulation.
I would like to have LJ potential with a cutoff distance of 2.5 interact between Type 1 atoms.
Between Type 2 atoms, I would like to have the same LJ potential with a different cutoff distance of 1.122462. Likewise between Type 1 and 2 atoms, the LJ potential with the cutoff distance of 1.122462 would still be applied.
Reading through the documentation and the mailing list, it seems that I need to use the pair_style hybrid to superimpose the same lj/cut for different cutoffs.
However, I came across the error: Expected integer parameter in input script or data file when I have the following commands
pair_style hybrid lj/cut 1.122462 lj/cut 2.5
pair_coeff 1 1 lj/cut 1.0 1.0 1.122462
pair_coeff 1 2 lj/cut 1.0 1.0 2.5
pair_coeff 2 2 lj/cut 1.0 1.0 2.5
Therefore, I tried with the second case which is:
pair_style lj/cut 2.5
pair_coeff 1 1 1.0 1.0 1.122462
pair_coeff 1 2 1.0 1.0 2.5
pair_coeff 2 2 1.0 1.0 2.5
For the second case where I did not use the pair_style hybrid, I was curious if lj/cut at 1.122462 remains in tact for the Type 1-Type 1 interaction, or if the pair_style lj/cut 2.5 overwrites all cutoff distance with 2.5 for every pair_coeff command.
If yes, I was curious if I could request for a comment on why, for the first case, pair_coeff 1 1 lj/cut 1.0 1.0 1.122462 would encounter the integer expectation error.
The cutoff and the epsilon or sigma do not have to be integers.
Thank you so much for your time and effort.
Sincerely,
Masato Koizumi