Hi.

For simulating of nitrogen and oxygen molecules I use TraPPE-Small model. Based on this model atoms of these molecules have electric charges. Also my simulation box has fix boundary condition at z direction. So, with respect to lammps manual I used coul/msm for coulombic term. But when I run my simulation I face with this error: **ERROR: Too many MSM grid levels** . I don’t know if this error relates to initial position of atoms or something else. I searched over net but I couldn’t find any solution.

You can also read the force field detail below

I would appreciate anyone help me to solve this problem

Vahid Ahmadi

```
variable epsilon_O equal 0.097373008691
variable sigma_O equal 3.02000
variable epsilon_N equal 0.07153934924399673
variable sigma_N equal 3.31000
variable epsilon_NO equal (${epsilon_O}*${epsilon_N})^0.5
variable sigma_NO equal (${sigma_O}+${sigma_N})/2
pair_style lj/cut/coul/msm 14.0 14.0
pair_modify tail yes
bond_style harmonic
angle_style harmonic
kspace_style msm 1.0e-4
kspace_modify cutoff/adjust no
pair_coeff * 2 0.0000 0.0000
pair_coeff * 4 0.0000 0.0000
pair_coeff 1 1 ${epsilon_O} ${sigma_O}
pair_coeff 3 3 ${epsilon_N} ${sigma_N}
pair_coeff 1 3 ${epsilon_NO} ${sigma_NO}
bond_style harmonic
angle_style harmonic
dihedral_style none
improper_style none
bond_coeff 1 5000.00 0.60500
bond_coeff 2 5000.00 0.55000
angle_coeff 1 500.0 180.00
angle_coeff 2 500.0 180.00
```