Sharon Hammes-Schiffer (born May 27, 1966) is a physical chemist who has contributed to theoretical and computational chemistry. She is currently a Sterling Professor of Chemistry at

Yale University Yale University is a Private university, private research university in New Haven, Connecticut. Established in 1701 as the Collegiate School, it is the List of Colonial Colleges, third-oldest institution of higher education in the United Sta ...

. She has served as senior editor and deputy editor of the ''

Journal of Physical Chemistry ''The Journal of Physical Chemistry A'' is a scientific journal which reports research on the chemistry of molecules - including their dynamics, spectroscopy, kinetics, structure, bonding, and quantum chemistry. It is published weekly by the Amer ...

'' and advisory editor for ''Theoretical Chemistry Accounts''. she is editor-in-chief of ''

Chemical Reviews ''Chemical Reviews'' is peer-reviewed scientific journal published twice per month by the American Chemical Society. It publishes review articles on all aspects of chemistry. It was established in 1924 by William Albert Noyes ( University of I ...

''. Hammes-Schiffer studies "chemical reactions in solution, in proteins and at electrochemical interfaces, particularly the transfer of charged particles driving many chemical and biological processes." Her research draws upon the areas of chemistry,

physics Physics is the natural science that studies matter, its fundamental constituents, its motion and behavior through space and time, and the related entities of energy and force. "Physical science is that department of knowledge which r ...

biology Biology is the scientific study of life. It is a natural science with a broad scope but has several unifying themes that tie it together as a single, coherent field. For instance, all organisms are made up of cells that process hereditary i ...

, and

computer science Computer science is the study of computation, automation, and information. Computer science spans theoretical disciplines (such as algorithms, theory of computation, information theory, and automation) to practical disciplines (includi ...

and is significant for the fields of

biochemistry Biochemistry or biological chemistry is the study of chemical processes within and relating to living organisms. A sub-discipline of both chemistry and biology, biochemistry may be divided into three fields: structural biology, enzymology and ...

, inorganic chemistry,

physical chemistry Physical chemistry is the study of macroscopic and microscopic phenomena in chemical systems in terms of the principles, practices, and concepts of physics such as motion, energy, force, time, thermodynamics, quantum chemistry, statistica ...

and

physical organic chemistry Physical organic chemistry, a term coined by Louis Hammett in 1940, refers to a discipline of organic chemistry that focuses on the relationship between chemical structures and reactivity, in particular, applying experimental tools of physical c ...

. A theoretician who works with computational models, Hammes-Schiffer blends classical molecular dynamics and quantum mechanics into theories that have direct relevance to a variety of experimental areas. In studying proton, electron and

proton coupled electron transfer A Proton-coupled electron transfer (PCET) is a chemical reaction that involves the transfer of electrons and protons from one atom to another. The term was originally coined for single proton, single electron processes that are concerted, but the ...

, Hammes-Schiffer has formulated a general theory of proton-coupled electron transfer reactions that explains the behavior of protons in energy conversion processes. Her research has enhanced the understanding of hydrogen tunneling and protein motion in enzyme catalysis. Her research group has also developed a nuclear-electronic orbital approach that allows scientists to incorporate nuclear quantum effects into electronic structure calculations. Her work has application to a variety of experimental results and has implications for areas such as protein engineering, drug design, catalyst of solar cells, and enzymatic reactions.

Early life and education

Hammes-Schiffer completed her B.A. in chemistry at

Princeton University Princeton University is a private research university in Princeton, New Jersey. Founded in 1746 in Elizabeth as the College of New Jersey, Princeton is the fourth-oldest institution of higher education in the United States and one of the ...

in 1988. She completed her Ph.D. in chemistry at Stanford University in 1993 after working with Hans C. Andersen. She then worked with John C. Tully at AT&T Bell Laboratories as a postdoctoral research scientist.

Career

Hammes-Schiffer held positions on the faculty at the

University of Notre Dame The University of Notre Dame du Lac, known simply as Notre Dame ( ) or ND, is a private Catholic university, Catholic research university in Notre Dame, Indiana, outside the city of South Bend, Indiana, South Bend. French priest Edward Sorin fo ...

as Clare Boothe Luce Assistant Professor of Chemistry and Biochemistry (1995-2000) and at Pennsylvania State University (2000-2012). In 2012 she joined the University of Illinois at Urbana-Champaign as Swanlund Professor of Chemistry, where she remained until 2017. Since then, she has led the Hammes-Schiffer Research Group at

, where she was named

John Gamble Kirkwood John "Jack" Gamble Kirkwood (May 30, 1907, Gotebo, Oklahoma – August 9, 1959, New Haven, Connecticut) was a noted chemist and physicist, holding faculty positions at Cornell University, the University of Chicago, California Institute of Technol ...

Professor of Chemistry in 2018, and Sterling Professor of Chemistry in 2021. Hammes-Schiffer is an author or co-author on nearly 200 papers, and has given more than 200 invited talks.

Research

Hammes-Schiffer's work delves primarily into three separate areas of chemistry: Proton-coupled electron transfer (PCET), Enzymatic Processes, and the Nuclear-Electronic Orbital method. A sect of this research engages in the study of the

Kinetic isotope effect In physical organic chemistry, a kinetic isotope effect (KIE) is the change in the reaction rate of a chemical reaction when one of the atoms in the reactants is replaced by one of its isotopes. Formally, it is the ratio of rate constants for th ...

, a difference in the reaction rate of a chemical based on what isotope is present.

Proton-coupled electron transfer (PCET)

The application of her work in PCET has elucidated the nature of various chemical mechanisms and led to her temperature dependence model of PCET rates. One such process, Quinol Oxidation, studied the

Ubiquinol A ubiquinol is an electron-rich (reduced) form of coenzyme Q (ubiquinone). The term most often refers to ubiquinol-10, with a 10-unit tail most commonly found in humans. The natural ubiquinol form of coenzyme Q is 2,3-dimethoxy-5-methyl-6-poly ...

and

Plastoquinol Plastoquinone (PQ) is an isoprenoid quinone molecule involved in the electron transport chain in the light-dependent reactions of photosynthesis. The most common form of plastoquinone, known as PQ-A or PQ-9, is a 2,3-dimethyl-1,4-benzoquinone mol ...

with regards to temperature, finding that the free energy of activation is greater for hydrogen than for

deuterium Deuterium (or hydrogen-2, symbol or deuterium, also known as heavy hydrogen) is one of two stable isotopes of hydrogen (the other being protium, or hydrogen-1). The nucleus of a deuterium atom, called a deuteron, contains one proton and one ...

, meaning the reaction is slower for hydrogen and therefore irreversible, if specific conditions are satisfied. This finding has since been used by other investigators to reinforce the notion that reactions may or may not be unidirectional by influencing reaction rates with the

kinetic isotope effect In physical organic chemistry, a kinetic isotope effect (KIE) is the change in the reaction rate of a chemical reaction when one of the atoms in the reactants is replaced by one of its isotopes. Formally, it is the ratio of rate constants for th ...

. Additionally, her study of PCET in Iron Bi-imidazoline complexes has refined common comprehension of PCET, having proven her theory that electron transfer rate increases under the kinetic isotope effect as "the proton transfer distance increases and the electron transfer distance decreases." These mechanisms have helped support the research of other PCET studies, with her main PCET paper, "Theoretical Studies of Proton-Coupled Electron Transfer Reactions", having been cited over 90 times by papers ranging from studying protein motion to enzyme dynamics.

Enzymatic processes

Hammes-Schiffer studies the effects of quantum tunnelling and hydrogen bonding on enzymatic reactions. Her work on Soybean Lipoxygenase-1 changed common perception of a previously proposed tunneling region diagram, finding that the temperature dependence of KIEs are inversely proportional to each other and that active environmental dynamics leads to less of the KIE and promotes catalysis. This finding should be applicable to any other enzymes which can transfer a proton due to the fact that there aren't as many enzymatic options for non-ionic transfer of a proton and therefore tunneling must be used throughout the process.

Nuclear-electronic orbital method (NEO)

Hammes-Schiffer has also pioneered work in what she calls the Nuclear-electronic orbital method (NEO) which allows for a more accurate estimate of nuclear properties such as

density Density (volumetric mass density or specific mass) is the substance's mass per unit of volume. The symbol most often used for density is ''ρ'' (the lower case Greek letter rho), although the Latin letter ''D'' can also be used. Mathematical ...

geometry Geometry (; ) is, with arithmetic, one of the oldest branches of mathematics. It is concerned with properties of space such as the distance, shape, size, and relative position of figures. A mathematician who works in the field of geometry is ...

, frequencies, electronic coupling, and nuclear motions. As described in her paper, "Incorporation of Nuclear Quantum effects in electronic structure,"

Radial basis function kernel In machine learning, the radial basis function kernel, or RBF kernel, is a popular kernel function used in various kernelized learning algorithms. In particular, it is commonly used in support vector machine classification. The RBF kernel on two ...

, a gaussian algorithm used to support vector machines, is applied to determine electronic and molecular orbitals. The NEO approach is specifically applicable in determining the exact mechanisms of hydrogen transfer reactions while accounting for other variables such as

quantum tunneling In physics, a quantum (plural quanta) is the minimum amount of any physical entity (physical property) involved in an interaction. The fundamental notion that a physical property can be "quantized" is referred to as "the hypothesis of quantizati ...

and

zero point energy Zero-point energy (ZPE) is the lowest possible energy that a quantum mechanical system may have. Unlike in classical mechanics, quantum systems constantly fluctuate in their lowest energy state as described by the Heisenberg uncertainty pr ...

. Hammes-Schiffer claims that the NEO approach is significantly advantageous over other methods that incorporate nuclear quantum effects because of the method's ability to calculate vibrational states, its avoidance of

Born–Oppenheimer approximation In quantum chemistry and molecular physics, the Born–Oppenheimer (BO) approximation is the best-known mathematical approximation in molecular dynamics. Specifically, it is the assumption that the wave functions of atomic nuclei and elect ...

and its apparent and inherent incorporation of

quantum effects Quantum mechanics is a fundamental theory in physics that provides a description of the physical properties of nature at the scale of atoms and subatomic particles. It is the foundation of all quantum physics including quantum chemistry, ...

. In her study, published in September 2016, Hammes-Schiffer contributed towards discovering the effects of the active site of the

magnesium Magnesium is a chemical element with the symbol Mg and atomic number 12. It is a shiny gray metal having a low density, low melting point and high chemical reactivity. Like the other alkaline earth metals (group 2 of the periodic ta ...

ion in the Scissile Phosphate cofactor complex. She discovered that rather than the magnesium ion lying in the center of the complex, the ion lies in a separate site, termed the Hoogsteen Face, where it lowers the pKa of the complex in order to facilitate a deprotonation reaction necessary for a self-cleavage reaction.

Honors and awards

Hammes-Schiffer is a Fellow of the American Physical Society (2010), the

American Chemical Society The American Chemical Society (ACS) is a scientific society based in the United States that supports scientific inquiry in the field of chemistry. Founded in 1876 at New York University, the ACS currently has more than 155,000 members at all ...

(2011), the

American Academy of Arts and Sciences The American Academy of Arts and Sciences (abbreviation: AAA&S) is one of the oldest learned societies in the United States. It was founded in 1780 during the American Revolution by John Adams, John Hancock, James Bowdoin, Andrew Oliver, a ...

(2012), the American Association for the Advancement of Science (2013), the National Academy of Sciences (2013), and the Biophysical Society (2015). She was elected as a member of the

International Academy of Quantum Molecular Science The International Academy of Quantum Molecular Science (IAQMS) is an international scientific learned society covering all applications of quantum theory to chemistry and chemical physics. It was created in Menton in 1967. The founding members we ...

in 2014. Hammes-Schiffer has received a number of awards, including the following: * 1996, Faculty Early Career Development (CAREER) Award,

National Science Foundation The National Science Foundation (NSF) is an independent agency of the United States government that supports fundamental research and education in all the non-medical fields of science and engineering. Its medical counterpart is the National ...

(NSF), for her work on "The Incorporation of Quantum Effects in the Simulation of Proton Transfer Reactions" * 2005, Iota Sigma Pi

Agnes Fay Morgan Research Award The Agnes Fay Morgan Research Award was established in 1951 by the Iota Sigma Pi honorary society for women in chemistry. The award is given for research achievement in chemistry or biochemistry to a woman not over forty years of age at the tim ...

* 2005, International Academy of Quantum Molecular Science Medal * 2008, American Chemical Society Akron Section Award * 2011, "Method to Extend Research in Time" (MERIT) award,

National Institutes of Health The National Institutes of Health, commonly referred to as NIH (with each letter pronounced individually), is the primary agency of the United States government responsible for biomedical and public health research. It was founded in the late ...

(NIH), a 10-year research grant to support her work * 2020, Bourke Award of the Royal Society of Chemistry *2021, American Chemical Society Award in Theoretical Chemistry *2021,

Willard Gibbs Josiah Willard Gibbs (; February 11, 1839 – April 28, 1903) was an American scientist who made significant theoretical contributions to physics, chemistry, and mathematics. His work on the applications of thermodynamics was instrumental in ...

Medal Award from American Chemical Society Chicago Section