USING QUANTUM MECHANICAL COMPUTATIONS TO UNDERSTAND THE STABILITY AND SPECTROSCOPIC PROPERTIES OF METAL HYDROXO CLUSTERS
Lindsay Wills1, Anna Oliveri2, Milton Jackson2, Darren Johnson1, Paul Cheong1.
1Oregon State University, Corvallis, OR, 2University of Oregon, Eugene, OR.
Metal hydroxo clusters exist in a vast array of structural forms under aqueous conditions, and some of these clusters have recently been used as precursors in sustainable techniques for making metal oxide thin films. There is no universal understanding for the formation of specific clusters over others, and discovery of new clusters is still rare and serendipitous. Therefore, methods to understand the stability of different clusters and uniquely identify clusters in solution are important to making high quality films. Quantum mechanical computations have been used to assist in understanding the thermodynamic and spectroscopic properties of metal hydroxo clusters. A group additivity method has been developed that can predict the stability of any metal hydroxo cluster using simple algebra with a mean unsigned error of 5.0 kcal/mol (2.5 %) and standard deviation of 8.5 kcal/mol (3.6 %), compared to quantum mechanical energies. Additionally, computations have been used to analyze the peaks in the vibrational and NMR spectra of these clusters. Identifying these clusters through vibrational and NMR spectroscopy is difficult due to the lack of knowledge regarding the signature peaks for each cluster. The vibrational modes and chemical shifts of several metal hydroxo clusters were computed, and spectra were generated based on the computed results and experimental spectra. These calculations show a new way for computations to further knowledge gained from experiments and to assist in material design and characterization.