Question about how to set the value of 4 pi epsilon in the Coulomb potential

Dear whom read my email:

When I used Lammps reduced unit, how should I set the value of 4piepsilon in the Coulomb potential?

to 1?

Since I’m a newbie in LAMMPS any kind of suggestions would be much appreciated.

For LJ units there is no Coulomb prefactor. Typical charge values
on a particle are +1 or -1 and the energy is simple QiQj/r.

If you are following a model in a paper, then it should simply

tell you what charge values to assign to each atom (in LJ units).

LAMMPS does the rest internally.