internal valence force field (IVFF)
A force field expressed in terms of bond-stretching, @A00346@-bending, torsional and other displacements directly connected to the structural parameters of the molecule: \[V=\frac{1}{2}\ \sum k_{ij}\ R_{i}\ R_{j}\] or \[V=\frac{1}{2}\ \sum K_{ij}\ R_{i}\ R_{j}\] where \(k\) (or \(K\)) are the @F02481@ and \(R\) the internal @V06588@ coordinates.
PAC, 1978, 50, 1707. (Definition and Symbolism of Molecular Force Constants) on page 1709 [Terms] [Paper]