error cpp

Hi everybody
I simulating a box of ionic liquid based imidazolium with lammps ,
my inpute file script is :

units real
dimension 3
boundary p p p
atom_style full
bond_style harmonic
angle_style harmonic
dihedral_style opls
improper_style cvff
pair_style lj/cut/coul/long 15.000
pair_modify mix arithmetic
kspace_style pppm 1.0e-4
neighbor 2.0 bin
neigh_modify delay 2 every 1 check yes

Please read about the error in doc/Section_errors.html.

You likely have bad dynamics.