Nonadiabatic Processes Relevant to HEDMS and Atmospheric Chemistry

摘要

There are three particularly notable aspects to this AFOSR sponsored work. The work with most enduring impact is our study on the polynitrogen molecules, (CH)nN5-n n=1,2,3,4. We found that these molecules have complicated photoelectron spectra owing to the existence of low-lying conical intersections or three-states with little or no symmetry. Further, this study identified a whole class of doublet radicals that are expected to exhibit low-lying three- state conical intersections. In the past, three-state intersections had been virtually ignored as too rare to be of consequence. Thus, these findings require a re-thinking of both the prevalence of three-state conical intersections and the electronic structure of a commonly occurring class of reactive chemical species. Secondly, we have made the electronic structure tools we have developed to locate and analyze two- and three-state conical intersections freely available to the general scientific community through the COLUMBUS suite of electronic structure codes. These extremely efficient multi- reference configuration- interaction-based codes are currently being maintained and extended through the combined efforts of Lischka (Vienna) and Sheppard (Argone). Finally, there is our theoretical determination of the absorption cross section for the alpha-beta transitions in O2 and NCl. We are to perform these highly accurate theoretical calculations, which are relevant to the energy transfer iodine laser systems, in a timely manner because of our participation in the AFOSR theoretical chemistry program.