Term: surface crossing
https://doi.org/10.1351/goldbook.S06166

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 Terms:
1) avoided crossing (<em>of potential-energy surfaces</em>) (http://doi.org/10.1351/goldbook.A00544).

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

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. https://doi.org/10.1351/goldbook.S06166

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