Advanced Modeling and Simulation of Solvent Extraction Systems - How Topological Data Analysis is Changing the Simulation Landscape

Michael Servis
Seminar

Molecular dynamics simulation is an emerging tool to describe complex solution phase association of molecular species, including solutions with applications to liquid/liquid separations. While simulations provide exact molecular positions, meaningfully quantifying the association and structure of those molecules requires additional modeling or analysis. This talk will cover several examples of generating insight into solution phase behavior using graph theoretic descriptions of molecular-scale correlations. In the first topic, intermolecular connectivity of liquid water is represented using graph theory. Molecular motions are identified through so-called transition matrices, where patterns in the changing connectivity between neighboring water molecules are identified to understand the dynamic pathways between configurations. In the second topic, PageRank is used to uniquely map the local connectivity pattern of an ion in solution to a single collective variable. That collective variable then can be used to drive the solvation environment of the ion in simulation from one structure to another through PageRank space. Lastly, simulations show that water protrusions form at the surfactant-laden liquid/liquid interface, leading to transfer of water between phases. Understanding the role of the surfactant in promoting protrusions, and therefore water transport, requires algorithmic identification of such interfacial features. We demonstrate that those protrusions can be identified by their spatial connectivity using network analysis.