Many reactions, particularly in photochemistry, combustion, atmospheric and interstellar chemistry, take place in more than one electronic state. The PES for these electronic states can intersect, and new methods have been developed to describe all the energy surfaces involved and their “interactions”. The methods and computer code to construct two intersecting electronic energy surfaces were completed and applied to the benchmark H + H2reaction. The quantum scattering on these surfaces revealed the subtle effect of the surface intersection on the differential reaction cross sections.
The code development for the general multi-state case is mostly completed, and is currently being tested for reactions involving H + H2 , H2 + H2+, and OH(2Â) + H2.