+int lennard_jones_check_2b_bond(t_moldyn *moldyn,t_atom *ai,t_atom *aj,u8 bc);
+
+/* lennard jones potential parameters */
+
+// silicon
+#define LJ_SIGMA_SI ((0.25*sqrt(3.0)*LC_SI)/1.122462)
+#define LJ_EPSILON_SI (2.1678*EV) // TODO
+
+// carbob
+#define LJ_SIGMA_C ((0.25*sqrt(3.0)*LC_C)/1.122462)
+#define LJ_EPSILON_C (2.1678*EV) // TODO