Title: surface crossing
Long Title: IUPAC Gold Book - surface crossing
DOI: 10.1351/goldbook.S06166
Status: current

Definition
In a diagram of electronic energy versus molecular geometry, the electronic energies of two states of different symmetry may be equal at certain geometrical parameters. At this point (unidimensional representation), line or surface (more than one dimension), the two potential-energy surfaces are said to cross one another.

Related Term
- avoided crossing: https://goldbook.iupac.org//terms/view/A00544

Source
- PAC, 1996, 68, 2223. 'Glossary of terms used in photochemistry (IUPAC Recommendations 1996)' on page 2279 (https://doi.org/10.1351/pac199668122223)

Other Outputs
- html: https://goldbook.iupac.org/terms/view/S06166/html
- json: https://goldbook.iupac.org/terms/view/S06166/json
- xml: https://goldbook.iupac.org/terms/view/S06166/xml

Citation: Citation: 'surface crossing' 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.S06166
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Accessed: 2026-05-18T11:17:04+00:00