gradual (sudden) potential-energy surface

https://doi.org/10.1351/goldbook.G02674
These terms relate to the steepness of the energy rise along the reaction path of a potential-energy (reaction) surface.
Source:
PAC, 1996, 68, 149. (A glossary of terms used in chemical kinetics, including reaction dynamics (IUPAC Recommendations 1996)) on page 167 [Terms] [Paper]