Westheimer empirical force field calculations

A system of analyzing the energy differences among molecules and among various geometries of a particular molecule has been developed, based on some fundamental notations formalized by Westheimer. The method is now known by the term molecular mechanics, although the expressions empirical force field calculations or the Westheimer method are sometimes applied. 

The molecular mechanics technique has been called by many different names, including Westheimer method, strain-energy method, conformational energy calculations, empirical potential energy calculations, atom-atom pair potential method, and force field calculations. Empirical force field is widely used, but somewhat long, and many authors omit empirical, leading to confusion with spectroscopic force field calculations. Molecular mechanics (11) now appears to be favored (10a) and is used (abbreviated as MM) throu out this chapter. 

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