Term: internal valence force field (IVFF)
https://doi.org/10.1351/goldbook.I03111

Definition:
A force field expressed in terms of bond-stretching, angle-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 force constants and R the internal valence coordinates.

Related Terms:
1) angle (http://doi.org/10.1351/goldbook.A00346).
2) valence (http://doi.org/10.1351/goldbook.V06588).
3) force constants (http://doi.org/10.1351/goldbook.F02481).

Source: PAC, 1978, 50, 1707. 'Definition and Symbolism of Molecular Force Constants' on page 1709 (https://doi.org/10.1351/pac197850111707)

Citation: 'internal valence force field (IVFF)' in IUPAC Compendium of Chemical Terminology, 5th ed. International Union of Pure and Applied Chemistry; 2025. Online version 5.0.0, 2025. https://doi.org/10.1351/goldbook.I03111

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