Force field methods torsional energies

Other important and effective approaches to computational chemistry are those called Empirical Force-Field methods (EFF methods), based on a mechanistic view of the molecule in terms of force constants of bonds, bending, torsion and other special interaction terms. The set of force constants constitutes a field of empirical parameters used for the calculation of molecular geometries and energies. 

The utility of these methods can be illustrated by investigating a generic molecular mechanics force field. The potential energy function for such a force field is usually divided into 4 parts bonds, bends, torsions, and non-bonded (electronic and van der waals) interactions. 

Table 4. Relative Energies and Associated Torsion Angles of Various Conformers of the [-Si(CH3)2 ] Model Compound As Calculated by the NR, PR, and FR Force Field Methods...

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