[lammps-users] use two cutoffs for pair_style lj/cut/coul/long

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1

Hello, LAMMPS users,

When I used two cutoffs in pair_coeff, LAMMPS gave ma an error message: Incorrect args for pair coefficients. Part of my input script is as following:

pair_style lj/cut/coul/long 2.5 7.5 #6.57353
pair_coeff 1 1 1.0 10.0 11.1246 100
pair_coeff 2 2 1.0 1.0 1.12246 5
pair_coeff 1 2 1.0 11.0 12.247 20
pair_modify shift yes
kspace_style pppm 0.001
kspace_modify slab 3.0

The charge for particle 1 is 10, so I would like to choose large cutoff for 1-1 coul interaction. The box size is 400X400.

From the manual, it supposes that I can use two cutoffs in pair_coeff, could anyone tells me why I got that error message? (If I use one cutoff, it is fine.)

All the best!

Dongsheng

2

For lj/cut/coul/long you can use 2 cutoffs in the pair_style command,
one for LJ, one for coul. Or you can use 1 cutoff, same for both lj
and coul.

But you cannot specify a coul cutoff in a pair_coeff command, only an
LJ cutoff. This is b/c the long-range solver requires a single
Coulombic cutoff for all atoms.

Steve