force-field.md

@@ -55,6 +55,10 @@ and of course we have
    - [Dipole Aspherical Ion Model](#daim)
    - [Steele wall](#steele)
 * [Intramolecular interactions](#intra)
+   - Harmonic bond
+   - Harmonic angle
+   - Dihedral angle
+   - Improper angle
 
 
 <a name="elec">