Title: transition structure
Long Title: IUPAC Gold Book - transition structure
DOI: 10.1351/goldbook.T06471
Status: current

Definition
A saddle point on a potential-energy surface. It has one negative force constant in the harmonic force constant matrix.

Related Terms
- activated complex: https://goldbook.iupac.org/terms/view/A00092
- potential-energy surface: https://goldbook.iupac.org/terms/view/P04780
- saddle point: https://goldbook.iupac.org/terms/view/C01145
- transition state: https://goldbook.iupac.org/terms/view/T06468

Source
- PAC, 1994, 66, 1077. 'Glossary of terms used in physical organic chemistry (IUPAC Recommendations 1994)' on page 1174 (https://doi.org/10.1351/pac199466051077)

Other Outputs
- html: https://goldbook.iupac.org/terms/view/T06471/html
- json: https://goldbook.iupac.org/terms/view/T06471/json
- xml: https://goldbook.iupac.org/terms/view/T06471/xml

Citation: Citation: 'transition structure' in IUPAC Compendium of Chemical Terminology, 5th ed. International Union of Pure and Applied Chemistry; 2025. Online version 5.0.0, 2025. 10.1351/goldbook.T06471
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Accessed: 2026-06-28T09:43:10+00:00