curve-crossing model in aerosol sizes, in atmospheric chemistry

https://dx.doi.org/10.1351/goldbook.CT07016
Model of organic reactivity that generates a reaction profile from curves that describe the energies of reactant, product, and intermediate electronic configurations (or, alternatively, reactant, product and intermediate electronic states) as a function of the reaction coordinate. The crossing reflects the electronic reorganization that accompanies the transformation of reactants and products.
Source:
PAC, 1999, 71, 1919 (Glossary of terms used in theoretical organic chemistry) on page 1933