Computational modeling provides great insight about chemical problems, enabling physical or theoretical, inorganic, and/or organic chemistry to be addressed, from the inherent complexities that can even be present in the smallest of molecules to questions about reaction pathways.  This presentation surveys several research projects, illustrating this breadth.Though diatomics are seemingly rather simple systems, the inherent challenges in modeling them are immense.   Molecules ranging from s-block systems to f-block systems have been studied, and effective (and ineffective) strategies for modeling their thermodynamic and spectroscopic properties are presented.  Highlighted will be work done in my mentorship of two undergraduate students (freshmen) in a project focusing upon lanthanides. Structural information for the lanthanide trifluorides was determined, using density functional theory (DFT) and MP2, in combination with both effective core potentials and all-electron basis sets.A continuing limitation in achieving high quality computational predictions for energetic predictions is the computational cost (computer time, memory, and disk space).  Ab initio composite methods are a useful way of reducing this cost, combining a series of less expensive methods to replicate the results that would be achieved with much more costly methods, and these methods have been widely used in chemistry.  While the replication is presumed, little work has been done to confirm the predictive abilities.  We have done this as an important step towards improving composite methods.In a collaboration with a synthetic organic chemist, I have used DFT to elucidate the reaction energetics of the isomerization reaction as disphosphine ligands migrate around a triosmium cluster. Two possible pathways have been reported: a one-step mechanism in which all ligands move about the equatorial plane of the cluster at once, and a pair-wise exchange of ligands across the Os-Os bond. The effects of different phosphine ligands upon the migratory preference were investigated.

Computational modeling of small to medium systems

248th National Meeting (2014)

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