Formulation of Molecular Mechanics

To more fully appreciate the molecular mechanics method, it is important to examine the underlying mathematical treatment. One of the fundamental theorems of molecular mechanics is that the total energy of a molecule can be divided into various readily identifiable parts. The total energy, E,ot.,i, of a molecule is thus divided into several parts, one of which is attributed to bond 

A more refined force field will also consider interactions or cross terms, such as stretch-bend, torsion-stretch, etc. These are usually small, and they can be neglected in the first approximation. Finally, other ad hoc terms such as hydrogen bonding have been used to take into account phenomena that are not properly accounted for otherwise. 

---