Ward H. Thompson
1567 Irving Hill Rd
Lawrence, KS 66045
Theoretical Chemical Dynamics in Liquids and Nanostructured Materials
Theoretical Physical Chemistry, chemical dynamics, vibrational spectroscopy, solvation, nanostructured and porous materials.
Our research focuses on the development and application of theoretical methods for describing chemical dynamics and spectroscopy in condensed phase systems. The emphasis is on understanding at a molecular level the fundamental behavior of interesting chemical systems and phenomena. The goal of our work is to develop accurate theoretical and computational approaches that can be feasibly applied to complex chemical problems including reactions in liquids and nanostructured environments. Some of the specific problems we are addressing are outlined below and more details are provided on our group website linked above.
Fluctuation Theory for Dynamics. We have recently developed an approach by which the activation energy for a rate constant or molecular timescale, which is a measure of how it changes with temperature, can be obtained from simulations at a single temperature. This is an improvement over the traditional way to calculate the activation energy from an Arrhenius plot of ln(k) versus 1/T. This method also allows the activation energy to be rigorously decomposed into the contributions from the kinetic energy and various interactions present in the system, thereby providing mechanistic information that is not available in any other way. We have shown that this approach can be implemented in classical or quantum mechanical simulations and is applicable to any dynamical timescale. We have demonstrated it by calculating the activation energies (or activation volumes) for reaction rate constants, diffusion coefficients, reorientational timescales, and viscosities.
Reactions and Spectroscopy in Nanostructured Porous Materials. Nanometer-sized cavities and pores can now be routinely generated in sol-gels, supramolecular assemblies, reverse micelles, zeolites, and even proteins, giving strong impetus to improving our understanding of chemistry in confined solvents.These cavities and pores can serve as nanoscale reaction vessels in which a chemical reaction takes place in the small pool of solvent allowed in the restricted space. However, there is currently little understanding about how these properties affect chemical dynamics. We are investigating both nanoscale silica pores and organic supramolecular assemblies as confining frameworks with a focus on understanding how the properties of the confining framework (as well as the species present) affect the structure (liquid layering and orientational ordering) and the dynamics (diffusion, reorientation, reactivity) of the confined liquid. In addition, it is often challenging to interpret measurements on these systems because many of the assumptions used for bulk liquids do not apply. Thus, we have developed simulations of (linear and nonlinear) vibrational spectra that can be directly compared to measurements to assist in extracting molecular-level information.
Catalysis. We frequently collaborate with experimentalists and other theorists interested in developing improved catalysts. In some of these studies, we investigate the reaction mechanisms in order to derive design principles that guide the development of improved catalysts. In others, we are focused on understanding the role of an amorphous support on the catalysis, particularly how the disorder of the material is manifested in the overall reaction kinetics.
Selected Publications —
Gomez, A., Piskulich, Z. A., Thompson, W. H., & Laage, D. Water Diffusion Proceeds via a Hydrogen-Bond Jump Exchange Mechanism. J. Phys. Chem. Lett., 2022, 13, 4660-4666.
Piskulich, Z. A., Laage, D. & Thompson, W. H. Using Activation Energies to Elucidate Mechanisms of Water Dynamics. J. Phys. Chem. A125, 9941–9952 (2021).
Wimalasiri, P.N., et al., Amorphous Silica Slab Models with Variable Surface Roughness and Silanol Density for Use in Simulations of Dynamics and Catalysis. Journal of Physical Chemistry C, 2021. 125(42): p. 23418-23434.
Senanayake, H.S., et al., Simulations of the IR and Raman spectra of water confined in amorphous silica slit pores. Journal of Chemical Physics, 2021. 154(10): p. 13.
Roget, S.A., et al., Identical Water Dynamics in Acrylamide Hydrogels, Polymers, and Monomers in Solution: Ultrafast IR Spectroscopy and Molecular Dynamics Simulations. Journal of the American Chemical Society, 2021. 143(36): p. 14855-14868.
Piskulich, Z.A. and W.H. Thompson, Examining the Role of Different Molecular Interactions on Activation Energies and Activation Volumes in Liquid Water. Journal of Chemical Theory and Computation, 2021. 17(5): p. 2659-2671.
Piskulich, Z.A., D. Laage, and W.H. Thompson, On the role of hydrogen-bond exchanges in the spectral diffusion of water. Journal of Chemical Physics, 2021. 154(6): p. 9.
Katiyar, A. and W.H. Thompson, Temperature Dependence of Peptide Conformational Equilibria from Simulations at a Single Temperature. Journal of Physical Chemistry A, 2021. 125(11): p. 2374-2384.
Borkowski, A.K., Z.A. Piskulich, and W.H. Thompson, Examining the Hofmeister Series through Activation Energies: Water Diffusion in Aqueous Alkali-Halide Solutions. Journal of Physical Chemistry B, 2021. 125(1): p. 350-359.
Yamada, S.A., et al., Effects of pore size on water dynamics in mesoporous silica. Journal of Chemical Physics, 2020. 152(15): p. 18.
Piskulich, Z.A. and W.H. Thompson, Temperature Dependence of the Water Infrared Spectrum: Driving Forces, Isosbestic Points, and Predictions. Journal of Physical Chemistry Letters, 2020. 11(18): p. 7762-7768.
Awards & Honors —
Sutton Family Research Impact Award Recipient