What Are Force Fields

There exists another possibility for describing a molecular system in the framework of classical mechanics. This approach assumes that the potential energy of a molecular system can be expanded in a Taylor series around its equilibrium geometry. By modifying this approach to make it transferable between different systems, molecular mechanics force fields are obtained. We describe later how this is done, how these force fields are used (see the section entitled Molecular Mechanics Force Fields), and compare the advantages and disadvantages of force fields of both types. 

Finally, we note that the use of the term force field in the literature is somewhat arbitrary. It is usually applied to both the set of potential energy functions and their corresponding parameters, but it is also common for some authors to refer to just a certain functional form as the force field. 

---