The Functional Form of Common Force Fields

A force field does not consist only of a mathematical eiqjression that describes the energy of a molecule with respect to the atomic coordinates. The second integral part is the parameter set itself. Two different force fields may share the same functional form, but use a completely different parameterization. On the other hand, different functional forms may lead to almost the same results, depending on the parameters. This comparison shows that force fields are empirical there is no correct form. Because some functional forms give better results than others, most of the implementations within the various available software packages (academic and commercial) are very similar. 

The mathematical formulation of a typical molecular mechanics force field, which is also called the potential energy function (PEF), is shown in Eq. (18). Do not wony yet about the necessary mathematical expressions - they will be explained in detail in the following sections  

The following sections give an overview of the functional form of the PFF and a short explanation of the various contributions to the total force field energy of a molecule or molecular system. 

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