Member of Yale faculty since 2018
Research in the Hammes-Schiffer group centers on the development and application of theoretical and computational methods for describing chemical reactions in condensed phases and at interfaces. Our overall objective is to elucidate the fundamental physical principles underlying charge transfer reactions, dynamics, and quantum mechanical effects in chemical, biological, and interfacial processes. Our research encompasses the development of analytical theories and computational methods, as well as applications to a wide range of experimentally relevant systems. The group is divided into three general areas: proton-coupled electron transfer reactions, enzymes and photoreceptor proteins, and non-Born-Oppenheimer electronic structure methods.
Proton-coupled electron transfer (PCET) reactions play a critical role in a wide range of chemical and biological processes. We have developed a general theory for PCET, which allows the calculation of rate constants and deuterium kinetic isotope effects, and have applied this theory to experimentally studied reactions in solution, proteins, and electrochemistry. We have also developed methodology to simulate the nonadiabatic ultrafast dynamics of photoinduced PCET reactions. Applications of these theories have assisted in the interpretation of experimental data and provided experimentally testable predictions. Our calculations have also guided the design of molecular electrocatalysts and photocatalysts for energy conversion devices such as solar cells. Current applications within the group include artificial photosynthetic systems, anthracene-phenol-pyridine triads, electrode/solution interfaces, graphite-conjugated catalysts, metal oxides, and metal-organic frameworks.
Our studies of biological processes have focused on the catalytic roles of protein motion, hydrogen bonding, hydrogen tunneling, electrostatics, conformational sampling, and metal ions. To study these properties, we have developed hybrid quantum/classical molecular dynamics approaches, as well as methods for calculating the vibrational shifts of nitrile probes in enzyme active sites. Many of the proteins studied undergo either thermal or photoinduced PCET. Current applications within the group include proteins containing redox-active tyrosine or tryptophan, ribonucleotide reductase, and photoreceptor proteins.
Our group has also developed the nuclear-electronic orbital (NEO) method for incorporating nuclear quantum effects and non-Born-Oppenheimer effects into quantum chemistry calculations. In the NEO approach, specified nuclei are treated quantum mechanically on the same level as the electrons using molecular orbital techniques. We have developed both multicomponent density functional theory (NEO-DFT) and multicomponent wavefunction methods. These NEO approaches include proton delocalization, zero-point energy, and hydrogen tunneling directly into geometry optimizations, reaction paths, and dynamics and avoid the Born-Oppenheimer separation between electrons and protons in a computationally practical manner. Time-dependent NEO approaches enable the simulation of nonequilibrium, real-time dynamics of chemical processes beyond the Born-Oppenheimer approximation.
B.A. Chemistry, Princeton University, 1988
Ph.D. Chemistry, Stanford University, 1993
Postdoctoral Fellow, AT&T Bell Laboratories, 1993-95
International Academy of Quantum Molecular Science Medal, 2005
American Chemical Society Akron Section Award, 2008
Fellow, American Physical Society, 2010
Fellow, American Chemical Society, 2011
Member, American Academy of Arts and Sciences, 2012
Fellow, American Association for the Advancement of Science, 2013
Member, U.S. National Academy of Sciences, 2013
Member, International Academy of Quantum Molecular Science, 2014
Fellow, Biophysical Society, 2015
G. M. Kosolapoff Award from Auburn University, 2019
Royal Society of Chemistry Bourke Award, 2020
American Chemical Society Award in Theoretical Chemistry, 2021
Joseph O. Hirschfelder Prize in Theoretical Chemistry, 2021
Willard Gibbs Medal Award, American Chemical Society Chicago Section, 2021