This award will support collaborative research between Dr. Roald Hoffmann, Cornell University and Dr. Jean-Yves Saillard, University of Rennes, France. Dr. Hoffmann, a Nobel Prize winner in chemistry, has built up at Cornell University one of the world's leading groups interested in bonding in molecules. Dr. Saillard is a distinguished crystallographer and applied theoretical chemist, who has collaborated successfully with Dr. Hoffmann over the last several years. Some elements readily form bonded diatomic pairs in molecular and extended solid state structures. Examples are sulfur (in pyrites, marcasites and many molecular complexes), phosphorus, boron, and silicon. On the other hand, oxygen and hydrogen diatomic molecular units in extended strucures are unknown (except for some peroxides) and diatomic carbon entities are rare, occuring mostly in rare earth and actinide structures. But the same units are known in discrete molecules. In this joint project Drs. Hoffman and Saillard will study theoretically the conditions for stabilizing diatomic oxygen, carbon, nitrogen and hydrogen in extended solid state materials
