In this SGER grant in the Theoretical and Computational Program of the Chemistry Division, Professor Adamowicz will develop new techniques dealing with the detailed interactions among the motions of electrons and nuclei in atoms and molecules. The new techniques will then be applied to obtain an understanding of highly energetic species. The PI will develop a new approach to treating the Born-Oppenheimer breakdown, using a non-adiabatic basis set and a variational functional for the total energy of the system. Instead of a rigorous separation of the internal and external motions, the new method is based on forcing the system to stop its translation in space and assume the desired rotational state by introducing penalty operators into the variational functional.