+double estimate_time_step(t_moldyn *moldyn,double nn_dist,double t);
+
+int moldyn_integrate(t_moldyn *moldyn);
+int velocity_verlet(t_moldyn *moldyn);
+
+double potential_harmonic_oscillator(t_moldyn *moldyn);
+int force_harmonic_oscillator(t_moldyn *moldyn);
+double potential_lennard_jones(t_moldyn *moldyn);
+int force_lennard_jones(t_moldyn *moldyn);