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Computational Chemistry and Geochemistry

The Chemical & Materials Sciences Division has signature capabilities in the area of development and application of computational methods to provide fundamental insight into the properties and processes of molecular and nanoscale systems in complex environments such as condensed phases and interfaces. We develop this fundamental understanding of complex molecular systems using accurate theoretical and computational approaches to study model systems. Accurate approaches, which capture the correct physics and chemistry, require:

• reliable descriptions of molecular interaction energies,
• consistent chemical physics theories that provide theoretical links between molecular interaction potentials and physical observables of interest, and
• robust simulation techniques for efficient computations within the theoretical framework.

We develop methods for understanding the correct physics and chemistry that must be included in intermolecular interactions to reliably reproduce a variety of experimental observables. The work in this area begins with accurate calculations of molecular interaction energies using electronic structure methods of known reliability, based upon careful benchmarking studies. Accurate energetics allow us to understand the features of potential energy surfaces that must be adequately described. We develop new approaches to fitting the accurate ab initio data to functional forms that provide unprecedented accuracy. We develop appropriate simulation techniques based on first-principles approaches to use accurate intermolecular interactions to simulate physical observables of interest at the macroscopic scale. Molecular theory and simulation techniques are used to understand the factors controlling reactions in homogeneous environments, particularly liquids and solids, and to understand transport and transformations in heterogeneous systems, such as liquid and mineral interfaces.

Computational approaches are used to study a wide variety of chemical, material, and geochemical problems including the following.

• Transport of ions and molecules at liquid and mineral interfaces, particular aqueous interfaces, to understand solvation structure and the factor that control solvation energies at interfaces.
• Chemical reactions in liquids and at liquid and mineral interfaces, to understand the energetic and dynamic factors controlling the mechanisms and rate of reactions.
• Energetic processes in covalently bonded amorphous materials, to understand processes leading to the degradation of oxide glasses.
• Structure and energetics of ion-ligand complexes, to understand the factors controlling the selectivity of ligand for separations of specific ions from complex solutions.
• Structure and energetics of nanostructured metal oxide materials, to provide the basis for understanding the reactive of these novel materials.
• Electron transfer at interfaces of metal oxides, included nanostructured materials, to understand the factors controlling the reactivity of nanoscale materials.