When I was trying to check my pair_coeff, I plotted the potential function u® according to the analytical form and then compared with the result given by pair_write.
lj/cut/coul/cut is the same as the analytical plot while lj/cut/coul/long is not. For lj/cut/coul/long, the minimum energy is about 6ev higher. Here is how I set the potential:
pair_style lj/cut/coul/long 10.0 10.0
#pair_style lj/cut/coul/cut 10.0 10.0
pair_coeff 1 1 0.00145 1.98
pair_coeff 2 2 0.00128 5.24
pair_modify shift yes mix arithmetic
kspace_style ewald/n 1.0e-8
pair_write 1 2 1000 r 1.8 10.0 table.txt LJ_Coul 1.18 -1.18
Is there anything wrong with my kpace setting?