particles { particle: particle_type=Argon, element_name=Ar, sigma=1, epsilon=1, sigma14=1, epsilon14=1, mass=1, free=3, charge=0; }; nonbonded_2body_potentials { ljspline: particle_type1=Argon, particle_type2=Argon, r_cut=2.3, r_l=1.9; };