Graduate Study in - Chemistry - Johns Hopkins University

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David R. Yarkony Theoretical Chemistry yarkony@jhu.edu According to the Born-Oppenheimer approximation nuclei move on a single potential energy surface created by the faster moving electrons. This approximation is at the heart of our description of most chemical processes. From protein folding to tribology to catalysis the Born Oppenheimer approximation rules. So why study nonadiabatic processes, processes in which the Born-Oppenheimer approximation breaks down. The answer is simple in the absence of nonadiabatic processes life on earth, as we know it would not exist. Light harvesting, vision and essential upper atmospheric processes depend on electronically nonadiabatic steps. Of course this has been known for decades. What is unusual and exciting is that in the last 10 years our way of thinking about electronically nonadiabatic processes has begun to change, and change dramatically. The changing face of nonadiabatic chemistry is the consequence of a rethinking of the role of surface intersections (conical intersections) of states of the same symmetry these processes. Once little more than a theoretical curiosity today conical intersections of two states of the same symmetry are now understood to be an essential part of nonadiabatic processes. This change in paradigm can dramatically change the predicted/expected rate of a nonadiabatic process. My research group has helped lead this revolution. Over the last decade we have developed the tools for studying conical intersections that define the state of the art in this area and as a result have lead the way in advancing the computational description of this singular consequence of the separation of nuclear and electronic time scales. More recently we have attacked the problem of nonadiabatic processes involving heavy atoms in which the spin-orbit interaction and Kramers’ degeneracy play an essential role. Our work in this area has provided the first ever location of a conical intersection in a polyatomic molecule based on ab initio wave functions with the spin-orbit interaction included in the Hamiltonian. We are currently building on our expertise in the description of the electronic structure aspects of nonadiabatic processes by developing fully quantum mechanical wave packet methods to quantify the role of conical intersections in nonadiabatic dynamics. In summary, nonadiabatic chemistry is an important field with a bright new future and we expect to continue to play a leading role in this area. Recent publications Nuclear Dynamics near conical intersections in the adiabatic representation: I. The effects of local topography on interstate transition: David R. Yarkony, J.Chem. Phys., 114, 2601-2613 (2001). Ph.D., University of California, Berkeley Postdoctoral, Massachusetts Institute of Technology Fellow, American Physical Society Alfred P. Sloan Research Fellowship Conical intersections: The New Conventional Wisdom – Feature Article, D. R. Yarkony, J. Phys. Chem. A 105, 6277-6293 (2001). On the Effects of Spin-Orbit Coupling on Conical Intersection Seams in Molecules with an Odd Number of Electrons. I: Locating the Seam; Spiridoula Matsika and David R. Yarkony, J. Chem. Phys. 115, 2038-2050 (2001). On the Effects of Spin-Orbit Coupling on Conical Intersection Seams in Molecules with an Odd Number of Electrons. II: Characterizing the local topography of the seam; Spiridoula Matsika and David R. Yarkony, J. Chem. Phys. 115,5066-5075, (2001). Graduate Study in Chemistry at The Johns Hopkins University 23
Instrumentation The department is well equipped with instrumentation to perform modern chemical research. Routine instrumentation is housed in the Instruments Facility in Remsen Hall and is maintained by staff within the department. In addition, there is a large variety of custom-built equipment in individual research laboratories. Our nuclear magnetic resonance facilities includes a 500 MHz Varian Unity instrument with full three-channel, gradients capability, a Varian 400 MHz spectrometer upgraded to a Unity console, and a 300 MHz Bruker AMX. The lower-field NMRs are used for more routine synthetic chemistry applications, while the high-field NMR is primarily dedicated to multi-dimensional analysis of proteins and nucleic acids. In addition, the undergraduate instructional laboratories house a Varian Mercury 200 MHz spectrometer that is also available for research use. In a joint initiative by the Departments of Biology, Biophysics, and Chemistry, the Krieger School of Arts and Sciences has commissioned the development of a Nuclear Magnetic Resonance Center for the study of the structure and dynamics of biological macromolecules. This facility will be constructed in connection with the new chemistry building, at a site bridging the chemistry and biology departments. The first instrument to be housed in this facility, a 600 MHz spectrometer, has recently been ordered. In addition to the NMR initiative, the department has recently received funding to establish a state of the art small molecule x-ray diffraction facility. This staffed facility, used for detailed molecular level structural characterization of new organic or inorganic compounds, will be available fo graduate student use. 24 Graduate Study in Chemistry at The Johns Hopkins University
Page 1 and 2: Chemistry Graduate Study in www.jhu
Page 3 and 4: Welcome Rendition of new chemistry
Page 5 and 6: Johns Hopkins University Establishm
Page 7 and 8: The Department of Chemistry Faculty
Page 9 and 10: Paul J. Dagdigian Experimental Phys
Page 11 and 12: D. Howard Fairbrother Ph.D., Northw
Page 13 and 14: Marc M. Greenberg Organic and Bioor
Page 15 and 16: Kenneth D. Karlin Ph. D., Columbia
Page 17 and 18: Gerald J. Meyer Inorganic Materials
Page 19 and 20: Gary H. Posner Organic Chemistry; M
Page 21 and 22: Joel R. Tolman Biophysical Chemistr
Page 23: Craig A. Townsend Bioorganic Chemis
Page 27 and 28: Useful Information Student Activiti
Page 29: Baltimore Map & Directions to Campu

Graduate Study in - Chemistry - Johns Hopkins University

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