Quantum-Designed Models of Bulk and Interfacial Solvation

Thomas Beck of the University of Cincinnati is supported by an award from the Chemical Theory, Models and Computational Methods program in the Division of Chemistry to develop new theoretical and computational methods to better understand complex liquid mixtures. Beck and his research group develop and use advanced computer simulations to investigate how molecules interact with each other to produce the great complexity in living things, industrial chemistry, household chemicals such as soaps, and battery materials. They use these advanced methods to model the basic properties of various charged particles (ions) in water and near the water surface. They also extend these techniques to studies of ions in organic liquids that are used in lithium ion batteries. In addition, the Beck group employs the new calculations to model phase separation in liquid mixtures relevant to industrial chemical processes. Accuracy is important because slight changes in the force fields that describe interactions between molecules often lead to completely different theoretical behaviors of the mixture. Gaining more insight into the interactions and resulting system properties results, for example, in the development of more efficient and safer battery materials. Communicating this basic science to the broader community is increasingly important, and Beck oversees a program at the Cincinnati Museum Center that will train 10 Ph.D. students from his Department to engage in effective science demonstrations on the floor of the museum.

Solvation and interfacial phenomena are central to a diverse array of physical, chemical, and biological systems including nanomaterials, surfactants, synthetic chemistry, membranes, proteins, and the energy sciences. While significant progress has been made in developing accurate models of complex ionic and molecular mixtures and interfaces, major challenges remain in building a predictive science of solvation. The principal objectives of this grant are threefold. The Beck group performs extensive ab initio quantum molecular dynamics simulations coupled with advanced statistical mechanical theories that establish a fundamental single-ion free energy scale in water and that explores the basic structure and dynamics of ion solvation in organic solvents. The team utilizes data from the ab initio simulations in constructing novel quantum-designed models that incorporate the essential physical components of solvation. They also applying these new models to challenging systems such as predicting liquid-liquid equilibrium and competitive solvent binding to ions in complex molecular mixtures. The theoretical methods employed include distributed charge multipole models and Drude oscillators optimized with evolutionary algorithms to mimic the electronic distributions in the condensed phase quantum simulation data. The resulting predictive computational models are employed in studies of interfacial electrostatics, specific ion effects in solution and near interfaces, and in ion solvation studies in organic solvents used in energy storage devices and in green chemistry processes.

This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.