Theoretical Studies of Inorganic, Organometallic, and Bioinorganic Systems
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Through this award funded by the Chemical Structure, Dynamics, and Mechanisms Program of the Division of Chemistry, Professor Michael B. Hall at Texas A&M University, College Station, will solve problems of current interest in catalytic reactions or in fundamental steps of catalytic cycles involving the activation of alkanes and dihydrogen by using modern quantum mechanical calculations. Full-gradient geometry optimizations with non-local density-functional theory and ab initio energy calculations, primarily coupled cluster and multireference configuration interaction, will be the primary computational tools. The research will study both natural enzymatic systems, particularly the hydrogenase enzymes, and totally synthetic systems, including model complexes for the hydrogenase systems and both thermal and photochemical activation of the systems that activate alkanes and dihydrogen. The project will involve close collaborations with experimental groups. These frontier problems also provide a testing ground for new functional and methodological developments. In that regard two developments are planned: one on the generalized molecular orbital method, which is a restricted-active-space self-consistent-field method to initialize multireference configuration interaction, and another on the "Fenske-Hall" approximate molecular orbital method. The Fenske-Hall method will be expanded to explore its applicability to combined quantum-mechanical/molecular-mechanical calculations. Its development will be particularly useful in modeling metalloenzymes and in metallo-clusters possibly as large as small nanocrystals. The close coupling of theory and experiment through collaborative arrangements will stimulate rapid progress on these important chemical problems. Alkane activation can play a role in making better use of these basic raw materials, and understanding how nature and artificial systems cleave and reassemble hydrogen can help in the development of a hydrogen economy. In addition to the education of students and postdoctoral associates at Texas A&M University, the large number of collaborators now associated with the laboratory brings the educational aspects to a much broader audience. In addition to the intellectual value in the development of the Fenske-Hall method, its simple graphical users interface (GUI) will be expanded to allow the method to be easily used by a wider audience and to be incorporated into teaching both undergraduate and graduate students about chemical bonding concepts.