Improved modeling of chemical interactions in solvent phase


Current Students: Mitch Groenenboom, Yasemin Basdogan, Nguyen Vo, Ethan Henderson

Overview: Our work in this field aims to unravel complicated reaction mechanisms where processes are not only determined by chemical transformations of intermediates in solution, but also interactions between the intermediates, the solvent, and other species in the solvent (e.g. counter ions from the electrolyte).  

Published work: In collaboration with Karl Johnson’s (Pitt-ChemE) group and Graeme Henkelman (UT Austin), we showed how atomic scale reaction pathways can be generated for complex solvent phase reactions without pre-defining collective variables for reaction pathways. A large number of reaction pathways for borohydride hydrolysis in water were discussed. 

See: Li, P; Henkelman, G.; Keith, J. A.; Johnson, J. K. “Elucidation of Aqueous Solvent Mediated Hydrogen Transfer Reactions by Ab Initio Molecular Dynamics and Nudged Elastic Band Studies of NaBH4 Hydrolysis” J. Phys. Chem. C 2014, 118, 21385-21399. DOI: 10.1021/jp507872d

Extending from the above work, Mitch showed how reaction energies from explicit solvation modeling are reasonably well reproduced using subsets of coordinates from the nudged-elastic band calculations embedded in continuum solvation models. This provides a simple way to incorporate higher levels of QM theory into computational simulations with explicit solvation. We then tested how reaction energetics differ when using different levels of quantum chemistry theory and found that level of theory plays a far lesser role in energetics than explicit solvent interactions and nearby counterions.

See: Mitchell C. Groenenboom, John A. Keith “Explicitly Unraveling the Roles of Counter Ions, Solvent Molecules, and Electron Correlation in Solution Phase Reaction Pathways”, J. Phys. Chem. B2016120, 10797-10807. DOI: 10.1021/acs.jpcb.6b07606.

Ongoing work: Our group is focusing on developing efficient mixed explicit/continuum solvation procedures to correct deficiencies in continuum solvation models. More accurate and reliable solvation energies would allow more predictive computational modeling of reaction mechanisms that involve explicit solvent interactions. It would also facilitate more accurate and reliable calculated descriptors for catalysis such as pKas, redox potentials, and hydricities. Accurately modeling molecules in solution phase would allow predictions of new and improved lanthanide extractants and environmentally greener chelants.  

Manuscripts on these topics are forthcoming in early 2017.

Please contact JAK if interested in collaborations.